Update lifetimes1.rs

Author: YRNS218

exercises/lifetimes/lifetimes1.rs

@@ -1,14 +1,4 @@
-// lifetimes1.rs
-// The Rust compiler needs to know how to check whether supplied references are
-// valid, so that it can let the programmer know if a reference is at risk of
-// going out of scope before it is used. Remember, references are borrows and do
-// not own their own data. What if their owner goes out of scope?
-// Execute `rustlings hint lifetimes1` or use the `hint` watch subcommand for a
-// hint.
 
-// I AM NOT DONE
-
-// 补充生命周期标注：返回引用的生命周期与入参x/y的生命周期相同（'a）
 fn longest<'a>(x: &'a str, y: &'a str) -> &'a str {
     if x.len() > y.len() {
         x