MutableString str = new MutableString("hello"); str[1] = 'a'; Console.WriteLine(str); // Output: hallo
MutableString str1 = new MutableString("hello"); MutableString str2 = new MutableString("world"); MutableString str3 = str1 + " " + str2; Console.WriteLine(str3); // Output: hello worldIn this example, we create two new MutableString objects with the values "hello" and "world", respectively. We then use the `+` operator to concatenate the two MutableStrings together with a space in between. Finally, we print out the new value of the MutableString using `Console.WriteLine()`. Overall, the MutableString class provides users with a way to easily manipulate strings in C# without having to constantly create new string objects.