update lifetime/basic.md

en/src/lifetime/basic.md

@@ -274,4 +274,85 @@ fn main()
 }
 ```
 
-## elision
+## Method
+Methods are annotated similarly to functions.
+
+**Example**
+```rust,editable
+struct Owner(i32);
+
+impl Owner {
+    // Annotate lifetimes as in a standalone function.
+    fn add_one<'a>(&'a mut self) { self.0 += 1; }
+    fn print<'a>(&'a self) {
+        println!("`print`: {}", self.0);
+    }
+}
+
+fn main() {
+    let mut owner = Owner(18);
+
+    owner.add_one();
+    owner.print();
+}
+```
+
+9、🌟🌟
+```rust,editable
+/* Make it work by adding proper lifetime annotations */
+struct ImportantExcerpt {
+    part: &str,
+}
+
+impl ImportantExcerpt {
+    fn level(&'a self) -> i32 {
+        3
+    }
+}
+
+fn main() {}
+```
+
+## Elision
+Some lifetime patterns are so comman that the borrow checker will allow you to omit them to save typing and to improve readablity.
+
+This is known as **Elision**. Elision exist in Rust only because these patterns are common.
+
+For a more comprehensive understanding of elision, please see [lifetime elision](https://doc.rust-lang.org/book/ch10-03-lifetime-syntax.html#lifetime-elision) in the official book.
+
+10、🌟🌟
+```rust,editable
+/* Remove all the lifetimes that can be elided */
+
+fn nput<'a>(x: &'a i32) {
+    println!("`annotated_input`: {}", x);
+}
+
+fn pass<'a>(x: &'a i32) -> &'a i32 { x }
+
+fn longest<'a, 'b>(x: &'a str, y: &'b str) -> &'a str {
+    x
+}
+
+struct Owner(i32);
+
+impl Owner {
+    // Annotate lifetimes as in a standalone function.
+    fn add_one<'a>(&'a mut self) { self.0 += 1; }
+    fn print<'a>(&'a self) {
+        println!("`print`: {}", self.0);
+    }
+}
+
+struct Person<'a> {
+    age: u8,
+    name: &'a str,
+}
+
+enum Either<'a> {
+    Num(i32),
+    Ref(&'a i32),
+}
+
+fn main() {}
+```

solutions/lifetime/basic.md

@@ -192,6 +192,54 @@ fn main()
 }
 ```
 
+9.
+```rust
+struct ImportantExcerpt<'a> {
+    part: &'a str,
+}
+
+impl<'a> ImportantExcerpt<'a> {
+    fn level(&'a self) -> i32 {
+        3
+    }
+}
+
+fn main() {}
+```
 
 
+10.
+```rust
 
+fn nput(x: &i32) {
+    println!("`annotated_input`: {}", x);
+}
+
+fn pass(x: &i32) -> &i32 { x }
+
+fn longest<'a, 'b>(x: &'a str, y: &'b str) -> &'a str {
+    x
+}
+
+struct Owner(i32);
+
+impl Owner {
+    // Annotate lifetimes as in a standalone function.
+    fn add_one(&mut self) { self.0 += 1; }
+    fn print(&self) {
+        println!("`print`: {}", self.0);
+    }
+}
+
+struct Person<'a> {
+    age: u8,
+    name: &'a str,
+}
+
+enum Either<'a> {
+    Num(i32),
+    Ref(&'a i32),
+}
+
+fn main() {}
+```