When the boy couldn't find his mother,he didn't know
问题描述:
When the boy couldn't find his mother,he didn't know
A.what to do B.how to do C.what to do it D.how to do it 要有解析
答
正选A
b中how to do ,do没有宾语 how 不能做宾语
c中 what to do it ,do的宾语重复 it 和what
d中 how to do it ,怎样做这件事 语义不通
重点 do 是及物动词