根据句意，用括号内所给单词的适当形式填空。

1. A glass is used for ________(drink) water.

2. What is the most         (use) invention in the world?

3. Do you know the          (heat) ice cream scoop?

4.This kind of bicycle was         (invent) by a middle school student.

5.What do you think of these         (invent)?