update readme.md

zh-CN/src/basic-types/char-bool-unit.md

@@ -27,7 +27,7 @@ fn print_char(c : char) {
 }
 ```
 
-### Bool
+### 布尔
 🌟
 ```rust, editable
 
@@ -53,7 +53,7 @@ fn main() {
 ```
 
 
-### Unit type
+### 单元类型
 🌟🌟
 ```rust,editable
 

zh-CN/src/basic-types/statements-expressions.md

@@ -1 +1,59 @@
 # Statements and Expressions
+
+### Examples
+```rust,editable
+fn main() {
+    let x = 5u32;
+
+    let y = {
+        let x_squared = x * x;
+        let x_cube = x_squared * x;
+
+        // This expression will be assigned to `y`
+        x_cube + x_squared + x
+    };
+
+    let z = {
+        // The semicolon suppresses this expression and `()` is assigned to `z`
+        2 * x;
+    };
+
+    println!("x is {:?}", x);
+    println!("y is {:?}", y);
+    println!("z is {:?}", z);
+}
+```
+
+### exercises
+🌟🌟
+```rust,editable
+// make it work with two ways: both modify the inner {}
+fn main() {
+   let v = {
+       let mut x = 1;
+       x += 2
+   };
+
+   assert_eq!(v, 3);
+}
+```
+
+🌟
+```rust,editable
+
+fn main() {
+   let v = (let x = 3);
+
+   assert!(v == 3);
+}
+```
+
+🌟
+```rust,editable
+
+fn main() {}
+
+fn sum(x: i32, y: i32) -> i32 {
+    x + y;
+}
+```