请问在一个句子中句首动词的时态是什么?以前老师讲过忘了
我做过这样两个题目:
①( )carefully before you buy a new house.
A. Thinking B. To think C. Thinks D.Think
答案是D,教科书讲解:祈使句以动词原形为首,故选D.
②( )the lesson before class gives me a better idea about what the teacher is going to teach.
A. Preview B. Previews C. Previewed D.Previewing
答案是D,教科书讲解:"( )the lesson before class "为本句的主词,故选动名词D当主词.
可是还是感觉没有明白用法以及上两题的区别。
有谁可以具体讲解一下吗,谢谢。