update readme.md

Readme.md

@@ -7,11 +7,68 @@ This book was designed for easily diving into Rust，and it's very easy to use:
 
 - There are three parts in each chapter: examples, exercises and practices
 - Covering nearly all aspects of Rust, such as **async/await, threads, sync primitives, optimizing and stand libraries** etc
-- Solutions
+- Solution for each exercise
 - Difficulty from easy to super hard: easy 🌟  medium 🌟🌟 hard 🌟🌟🌟  super hard 🌟🌟🌟🌟
 - Both [English](https://practice.rs) and [Chinsese](https://zh.practice.rs) are supported
 
+## Some of our exercises
 
+🌟🌟🌟 Tuple struct looks similar to tuples, it has added meaning the struct name provides but has no named fields. It's useful when you want give the whole tuple a name, but don't care the fields's names.
+
+```rust
+
+// fix the error and fill the blanks
+struct Color(i32, i32, i32);
+struct Point(i32, i32, i32);
+fn main() {
+    let v = Point(___, ___, ___);
+    check_color(v);
+}   
+
+fn check_color(p: Color) {
+    let (x, _, _) = p;
+    assert_eq!(x, 0);
+    assert_eq!(p.1, 127);
+    assert_eq!(___, 255);
+ }
+```
+
+🌟🌟 Within the destructuring of a single variable, both by-move and by-reference pattern bindings can be used at the same time. Doing this will result in a partial move of the variable, which means that parts of the variable will be moved while other parts stay. In such a case, the parent variable cannot be used afterwards as a whole, however the parts that are only referenced (and not moved) can still be used.
+```rust
+
+// fix errors to make it work
+#[derive(Debug)]
+struct File {
+    name: String,
+    data: String,
+}
+fn main() {
+    let f = File {
+        name: String::from("readme.md"),
+        data: "Rust By Practice".to_string()
+    };
+
+    let _name = f.name;
+
+    // ONLY modify this line
+    println!("{}, {}, {:?}",f.name, f.data, f);
+} 
+```
+
+🌟🌟 A match guard is an additional if condition specified after the pattern in a match arm that must also match, along with the pattern matching, for that arm to be chosen.
+```rust,editable
+
+// fill in the blank to make the code work, `split` MUST be used
+fn main() {
+    let num = Some(4);
+    let split = 5;
+    match num {
+        Some(x) __ => assert!(x < split),
+        Some(x) => assert!(x >= split),
+        None => (),
+    }
+}
+```
 
 ## ToC
 - [Variables](src/variables.md)