用括号中动词的适当形式填空:3、They ( )(catch)butterflies now.4、My father ( )(work)in his office.

问题描述:

用括号中动词的适当形式填空:3、They ( )(catch)butterflies now.4、My father ( )(work)in his office.

are catching
is working
这两个句子都是现在进行时,结构为be+v-ing形式