状语从句练习he did not buy the book ,beacuse it was too expensive.为什么在这里过去时还用buy ,而不用bought
问题描述：
状语从句练习
he did not buy the book ,beacuse it was too expensive.
为什么在这里过去时还用buy ,而不用bought
答
这个是一般过去时的否定句啊……
did not 后面要跟动词原形
答
did not 过去式的否定形式后加动词原形呀
答
did not 后面是动词原形啊
答
前面疑问词是did
后面的动词要用原型
答
buy是实义动词,其否定形式要用助动词 do not(过去时时用did not）,其人称和时态的变化都在助动词do oot上,而不需要改变buy.