海水温度高时海水淡化装置真空度下降可能是因为（）。
A.海水含气量增多
B.冷却能力下降
C.喷射泵抽气能力降低
D.B+C
参考答案：D
Michael really has a gift ______ playing the piano so his teacher decided to make a pianist of him.
A．on
B．about
C．into
D．for
电压负反馈断线时操作时出现什么现象？
