— When would it be        for you to go to the science museum with me?

— I am free this Friday afternoon. Let’s meet at 2 p.m. at the school gate.

A．convenient

B．pleasant

C．necessary

D．familiar

水轮机是将水能转换为机械能的一种（）。

A.水能机械

B.水力机械

C.水力机器

D.水能机器