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)?