diff --git a/exercises/functions/functions1.rs b/exercises/functions/functions1.rs
index 40ed9a07..6a231f32 100644
--- a/exercises/functions/functions1.rs
+++ b/exercises/functions/functions1.rs
@@ -3,8 +3,12 @@
 // Execute `rustlings hint functions1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     call_me();
 }
+
+fn call_me(){
+
+}
diff --git a/exercises/functions/functions2.rs b/exercises/functions/functions2.rs
index 5154f34d..44d094ad 100644
--- a/exercises/functions/functions2.rs
+++ b/exercises/functions/functions2.rs
@@ -3,13 +3,13 @@
 // Execute `rustlings hint functions2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     call_me(3);
 }
 
-fn call_me(num:) {
+fn call_me(num: i32) {
     for i in 0..num {
         println!("Ring! Call number {}", i + 1);
     }
diff --git a/exercises/functions/functions3.rs b/exercises/functions/functions3.rs
index 74f44d6d..ea24f10a 100644
--- a/exercises/functions/functions3.rs
+++ b/exercises/functions/functions3.rs
@@ -3,10 +3,10 @@
 // Execute `rustlings hint functions3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
-    call_me();
+    call_me(100);
 }
 
 fn call_me(num: u32) {
diff --git a/exercises/functions/functions4.rs b/exercises/functions/functions4.rs
index 77c4b2aa..ab1239a1 100644
--- a/exercises/functions/functions4.rs
+++ b/exercises/functions/functions4.rs
@@ -8,14 +8,14 @@
 // Execute `rustlings hint functions4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     let original_price = 51;
     println!("Your sale price is {}", sale_price(original_price));
 }
 
-fn sale_price(price: i32) -> {
+fn sale_price(price: i32) -> i32 {
     if is_even(price) {
         price - 10
     } else {
diff --git a/exercises/functions/functions5.rs b/exercises/functions/functions5.rs
index f1b63f48..86b9fb32 100644
--- a/exercises/functions/functions5.rs
+++ b/exercises/functions/functions5.rs
@@ -3,7 +3,7 @@
 // Execute `rustlings hint functions5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     let answer = square(3);
@@ -11,5 +11,6 @@ fn main() {
 }
 
 fn square(num: i32) -> i32 {
-    num * num;
+    // num * num;
+    num * num
 }
diff --git a/exercises/if/if1.rs b/exercises/if/if1.rs
index 4734d78f..831ea008 100644
--- a/exercises/if/if1.rs
+++ b/exercises/if/if1.rs
@@ -2,13 +2,18 @@
 //
 // Execute `rustlings hint if1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 pub fn bigger(a: i32, b: i32) -> i32 {
     // Complete this function to return the bigger number!
     // Do not use:
     // - another function call
     // - additional variables
+    if ( a >= b ){
+        a
+    }else{
+        b
+    }
 }
 
 // Don't mind this for now :)
diff --git a/exercises/if/if2.rs b/exercises/if/if2.rs
index f512f13f..2b446114 100644
--- a/exercises/if/if2.rs
+++ b/exercises/if/if2.rs
@@ -5,13 +5,17 @@
 //
 // Execute `rustlings hint if2` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 pub fn foo_if_fizz(fizzish: &str) -> &str {
     if fizzish == "fizz" {
         "foo"
+    // } else if (fizzish == "fuzz") {
+    //     "bar"
+    } else if fizzish == "fuzz" {
+        "bar"
     } else {
-        1
+        "baz"
     }
 }
 
diff --git a/exercises/if/if3.rs b/exercises/if/if3.rs
index 16962740..ef8b8a99 100644
--- a/exercises/if/if3.rs
+++ b/exercises/if/if3.rs
@@ -2,17 +2,18 @@
 //
 // Execute `rustlings hint if3` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 pub fn animal_habitat(animal: &str) -> &'static str {
     let identifier = if animal == "crab" {
         1
     } else if animal == "gopher" {
-        2.0
+        // 2.0
+        2
     } else if animal == "snake" {
         3
     } else {
-        "Unknown"
+        4
     };
 
     // DO NOT CHANGE THIS STATEMENT BELOW
diff --git a/exercises/intro/intro1.rs b/exercises/intro/intro1.rs
index 37fa0112..b15a6ca9 100644
--- a/exercises/intro/intro1.rs
+++ b/exercises/intro/intro1.rs
@@ -13,7 +13,7 @@
 // Execute `rustlings hint intro1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     println!("Hello and");
diff --git a/exercises/intro/intro2.rs b/exercises/intro/intro2.rs
index 990b20f0..5c576af3 100644
--- a/exercises/intro/intro2.rs
+++ b/exercises/intro/intro2.rs
@@ -5,8 +5,9 @@
 // Execute `rustlings hint intro2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
-    println!("Hello {}!");
+    let string: String = "World".to_string();
+    println!("Hello {}!", string);
 }
diff --git a/exercises/primitive_types/primitive_types1.rs b/exercises/primitive_types/primitive_types1.rs
index 36633400..9b79a379 100644
--- a/exercises/primitive_types/primitive_types1.rs
+++ b/exercises/primitive_types/primitive_types1.rs
@@ -3,7 +3,7 @@
 // Fill in the rest of the line that has code missing! No hints, there's no
 // tricks, just get used to typing these :)
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     // Booleans (`bool`)
@@ -13,7 +13,8 @@ fn main() {
         println!("Good morning!");
     }
 
-    let // Finish the rest of this line like the example! Or make it be false!
+    let is_evening = true;// Finish the rest of this line like the example! Or make it be false!
+    // let is_evening = false;
     if is_evening {
         println!("Good evening!");
     }
diff --git a/exercises/primitive_types/primitive_types2.rs b/exercises/primitive_types/primitive_types2.rs
index f1616ed3..dd125581 100644
--- a/exercises/primitive_types/primitive_types2.rs
+++ b/exercises/primitive_types/primitive_types2.rs
@@ -3,7 +3,7 @@
 // Fill in the rest of the line that has code missing! No hints, there's no
 // tricks, just get used to typing these :)
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     // Characters (`char`)
@@ -19,7 +19,9 @@ fn main() {
         println!("Neither alphabetic nor numeric!");
     }
 
-    let // Finish this line like the example! What's your favorite character?
+    let your_character = 'A';// Finish this line like the example! What's your favorite character?
+    let your_character = '😘';
+    let your_character = '你';
     // Try a letter, try a number, try a special character, try a character
     // from a different language than your own, try an emoji!
     if your_character.is_alphabetic() {
diff --git a/exercises/primitive_types/primitive_types3.rs b/exercises/primitive_types/primitive_types3.rs
index 8b0de44e..6cfd06e2 100644
--- a/exercises/primitive_types/primitive_types3.rs
+++ b/exercises/primitive_types/primitive_types3.rs
@@ -5,10 +5,10 @@
 // Execute `rustlings hint primitive_types3` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
-    let a = ???
+    let a = ["nihao";100];
 
     if a.len() >= 100 {
         println!("Wow, that's a big array!");
@@ -16,4 +16,6 @@ fn main() {
         println!("Meh, I eat arrays like that for breakfast.");
         panic!("Array not big enough, more elements needed")
     }
+
+    // println!("{:?}", a);
 }
diff --git a/exercises/primitive_types/primitive_types4.rs b/exercises/primitive_types/primitive_types4.rs
index d44d8776..22e1c8c6 100644
--- a/exercises/primitive_types/primitive_types4.rs
+++ b/exercises/primitive_types/primitive_types4.rs
@@ -5,13 +5,14 @@
 // Execute `rustlings hint primitive_types4` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 #[test]
 fn slice_out_of_array() {
     let a = [1, 2, 3, 4, 5];
 
-    let nice_slice = ???
+    // let nice_slice = &a[1..3];
+    let nice_slice = &a[1..4];
 
     assert_eq!([2, 3, 4], nice_slice)
 }
diff --git a/exercises/primitive_types/primitive_types5.rs b/exercises/primitive_types/primitive_types5.rs
index f646986e..c9228cc9 100644
--- a/exercises/primitive_types/primitive_types5.rs
+++ b/exercises/primitive_types/primitive_types5.rs
@@ -5,11 +5,13 @@
 // Execute `rustlings hint primitive_types5` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     let cat = ("Furry McFurson", 3.5);
-    let /* your pattern here */ = cat;
+    // let /* your pattern here */ = cat;
+    let (name, age) = cat;
+    let (name, age): (&str, f32) = cat;
 
     println!("{} is {} years old.", name, age);
 }
diff --git a/exercises/primitive_types/primitive_types6.rs b/exercises/primitive_types/primitive_types6.rs
index 07cc46c6..5f7ff268 100644
--- a/exercises/primitive_types/primitive_types6.rs
+++ b/exercises/primitive_types/primitive_types6.rs
@@ -3,16 +3,17 @@
 // Use a tuple index to access the second element of `numbers`. You can put the
 // expression for the second element where ??? is so that the test passes.
 //
-// Execute `rustlings hint primitive_types6` or use the `hint` watch subcommand
+// Execute `    ` or use the `hint` watch subcommand
 // for a hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 #[test]
 fn indexing_tuple() {
     let numbers = (1, 2, 3);
     // Replace below ??? with the tuple indexing syntax.
-    let second = ???;
+    // 用index取元组中的值
+    let second = numbers.1;
 
     assert_eq!(2, second,
         "This is not the 2nd number in the tuple!")
diff --git a/exercises/quiz1.rs b/exercises/quiz1.rs
index 4ee5ada7..4e3fe467 100644
--- a/exercises/quiz1.rs
+++ b/exercises/quiz1.rs
@@ -13,10 +13,19 @@
 //
 // No hints this time ;)
 
-// I AM NOT DONE
+// I AM DONE
 
 // Put your function here!
-// fn calculate_price_of_apples {
+fn calculate_price_of_apples(count: i32) -> i32{
+    let price: i32;
+    if count <= 40 && count > 0{
+        count * 2
+    } else if count > 40 {
+        count * 1
+    } else {
+        0
+    }
+}
 
 // Don't modify this function!
 #[test]
diff --git a/exercises/variables/variables1.rs b/exercises/variables/variables1.rs
index b3e089a5..ba90630f 100644
--- a/exercises/variables/variables1.rs
+++ b/exercises/variables/variables1.rs
@@ -5,9 +5,9 @@
 // Execute `rustlings hint variables1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
-    x = 5;
+    let x = 5;
     println!("x has the value {}", x);
 }
diff --git a/exercises/variables/variables2.rs b/exercises/variables/variables2.rs
index e1c23edf..bbfc0288 100644
--- a/exercises/variables/variables2.rs
+++ b/exercises/variables/variables2.rs
@@ -3,10 +3,13 @@
 // Execute `rustlings hint variables2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
-    let x;
+    // let x: i32 = 0;
+    // 类型推断
+    // Type inference
+    let x = 0; 
     if x == 10 {
         println!("x is ten!");
     } else {
diff --git a/exercises/variables/variables3.rs b/exercises/variables/variables3.rs
index 86bed419..03e1b79f 100644
--- a/exercises/variables/variables3.rs
+++ b/exercises/variables/variables3.rs
@@ -3,9 +3,9 @@
 // Execute `rustlings hint variables3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
-    let x: i32;
+    let x: i32 = 10;
     println!("Number {}", x);
 }
diff --git a/exercises/variables/variables4.rs b/exercises/variables/variables4.rs
index 5394f394..7f596427 100644
--- a/exercises/variables/variables4.rs
+++ b/exercises/variables/variables4.rs
@@ -3,10 +3,12 @@
 // Execute `rustlings hint variables4` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
-    let x = 3;
+    // Variable bindings are immutable by default
+    // 变量绑定默认是不可变的
+    let mut x = 3;
     println!("Number {}", x);
     x = 5; // don't change this line
     println!("Number {}", x);
diff --git a/exercises/variables/variables5.rs b/exercises/variables/variables5.rs
index a29b38be..88bd21e9 100644
--- a/exercises/variables/variables5.rs
+++ b/exercises/variables/variables5.rs
@@ -3,11 +3,13 @@
 // Execute `rustlings hint variables5` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn main() {
     let number = "T-H-R-E-E"; // don't change this line
     println!("Spell a Number : {}", number);
-    number = 3; // don't rename this variable
-    println!("Number plus two is : {}", number + 2);
+    // number = 3; // don't rename this variable
+    // Shadowing
+    let number = 3;
+    println!("Number plus two is : {}",  number + 2);
 }
diff --git a/exercises/variables/variables6.rs b/exercises/variables/variables6.rs
index 853183ba..4ce09b33 100644
--- a/exercises/variables/variables6.rs
+++ b/exercises/variables/variables6.rs
@@ -3,9 +3,11 @@
 // Execute `rustlings hint variables6` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
+// I AM DONE
 
-const NUMBER = 3;
+// Constants types must also always be annotated.
+// 常量的类型总是需要标注
+const NUMBER: i32 = 3;
 fn main() {
     println!("Number {}", NUMBER);
 }
diff --git a/exercises/vecs/vecs1.rs b/exercises/vecs/vecs1.rs
index 65b7a7f8..3a09a942 100644
--- a/exercises/vecs/vecs1.rs
+++ b/exercises/vecs/vecs1.rs
@@ -7,11 +7,18 @@
 //
 // Execute `rustlings hint vecs1` or use the `hint` watch subcommand for a hint.
 
-// I AM NOT DONE
+// I AM DONE
 
 fn array_and_vec() -> ([i32; 4], Vec<i32>) {
     let a = [10, 20, 30, 40]; // a plain array
-    let v = // TODO: declare your vector here with the macro for vectors
+    // let v = // TODO: declare your vector here with the macro for vectors
+    // let mut v = Vec::new();
+    // v.push(10);
+    // v.push(20);
+    // v.push(30);
+    // v.push(40);
+
+    let v = vec![10, 20, 30, 40];
 
     (a, v)
 }
diff --git a/exercises/vecs/vecs2.rs b/exercises/vecs/vecs2.rs
index e92c970a..a81dd179 100644
--- a/exercises/vecs/vecs2.rs
+++ b/exercises/vecs/vecs2.rs
@@ -13,7 +13,7 @@ fn vec_loop(mut v: Vec<i32>) -> Vec<i32> {
     for element in v.iter_mut() {
         // TODO: Fill this up so that each element in the Vec `v` is
         // multiplied by 2.
-        ???
+        *element = *element * 2;
     }
 
     // At this point, `v` should be equal to [4, 8, 12, 16, 20].
@@ -24,7 +24,7 @@ fn vec_map(v: &Vec<i32>) -> Vec<i32> {
     v.iter().map(|element| {
         // TODO: Do the same thing as above - but instead of mutating the
         // Vec, you can just return the new number!
-        ???
+        element * 2
     }).collect()
 }