use ref

solutions/ownership/ownership.md

@@ -163,7 +163,7 @@ fn main() {
     let t = (String::from("hello"), String::from("world"));
 
     // fill the blanks
-    let (s1, s2) = t.clone();
+    let (ref s1, ref s2) = t;
 
     println!("{:?}, {:?}, {:?}", s1, s2, t); // -> "hello", "world", ("hello", "world")
 }