_____,liquids can be changed into gases.A To be heated B Heated

题目

_____,liquids can be changed into gases.A To be heated B Heated
加热,固体会变成液体.两选项表达的是啥?

答案

选B.这是考察独立主格结构.
A的话,是不定式表将来.
B的话,是过去分词表示被动和完成.
因为加热后,液体会变成气态,所以用B,一般现在的时态就可以了.相当于：
When it is heated,liquids can be changed into gases.