diff --git a/exercises/09_strings/strings1.rs b/exercises/09_strings/strings1.rs
index f50e1fa988..e789b8f0fc 100644
--- a/exercises/09_strings/strings1.rs
+++ b/exercises/09_strings/strings1.rs
@@ -5,13 +5,11 @@
 // Execute `rustlings hint strings1` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let answer = current_favorite_color();
     println!("My current favorite color is {}", answer);
 }
 
 fn current_favorite_color() -> String {
-    "blue"
+    "blue".to_string()
 }
diff --git a/exercises/09_strings/strings2.rs b/exercises/09_strings/strings2.rs
index 4d95d16a16..ca16ea3d03 100644
--- a/exercises/09_strings/strings2.rs
+++ b/exercises/09_strings/strings2.rs
@@ -5,11 +5,9 @@
 // Execute `rustlings hint strings2` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn main() {
     let word = String::from("green"); // Try not changing this line :)
-    if is_a_color_word(word) {
+    if is_a_color_word(&word) {
         println!("That is a color word I know!");
     } else {
         println!("That is not a color word I know.");
diff --git a/exercises/09_strings/strings3.rs b/exercises/09_strings/strings3.rs
index 384e7ce3ea..8b686eed65 100644
--- a/exercises/09_strings/strings3.rs
+++ b/exercises/09_strings/strings3.rs
@@ -3,21 +3,19 @@
 // Execute `rustlings hint strings3` or use the `hint` watch subcommand for a
 // hint.
 
-// I AM NOT DONE
-
 fn trim_me(input: &str) -> String {
-    // TODO: Remove whitespace from both ends of a string!
-    ???
+    // Remove whitespace from both ends of a string!
+    input.trim().to_string()
 }
 
 fn compose_me(input: &str) -> String {
-    // TODO: Add " world!" to the string! There are multiple ways to do this!
-    ???
+    // Add " world!" to the string! There are multiple ways to do this!
+    input.to_string() + " world!"
 }
 
 fn replace_me(input: &str) -> String {
-    // TODO: Replace "cars" in the string with "balloons"!
-    ???
+    // Replace "cars" in the string with "balloons"!
+    input.replace("cars", "balloons")
 }
 
 #[cfg(test)]
diff --git a/exercises/09_strings/strings4.rs b/exercises/09_strings/strings4.rs
index e8c54acc55..9c2a0c7206 100644
--- a/exercises/09_strings/strings4.rs
+++ b/exercises/09_strings/strings4.rs
@@ -7,8 +7,6 @@
 //
 // No hints this time!
 
-// I AM NOT DONE
-
 fn string_slice(arg: &str) {
     println!("{}", arg);
 }
@@ -17,14 +15,14 @@ fn string(arg: String) {
 }
 
 fn main() {
-    ???("blue");
-    ???("red".to_string());
-    ???(String::from("hi"));
-    ???("rust is fun!".to_owned());
-    ???("nice weather".into());
-    ???(format!("Interpolation {}", "Station"));
-    ???(&String::from("abc")[0..1]);
-    ???("  hello there ".trim());
-    ???("Happy Monday!".to_string().replace("Mon", "Tues"));
-    ???("mY sHiFt KeY iS sTiCkY".to_lowercase());
+    string_slice("blue");
+    string("red".to_string());
+    string(String::from("hi"));
+    string("rust is fun!".to_owned());
+    string("nice weather".into());
+    string(format!("Interpolation {}", "Station"));
+    string_slice(&String::from("abc")[0..1]);
+    string_slice("  hello there ".trim());
+    string("Happy Monday!".to_string().replace("Mon", "Tues"));
+    string("mY sHiFt KeY iS sTiCkY".to_lowercase());
 }