__he entered the university,his english has been much improved.A after B since C beforeA和C用于怎样的句子中?
问题描述：
__he entered the university,his english has been much improved.A after B since C before
A和C用于怎样的句子中?
答
答案是 B since
其它选项 引导从句 时态不符
答
答案是B，因为后面出现了完成时。
A和C的话，后面动词是动名词形式。
答
B,因后句是完成时态
答
B
since，完成时的特征词：自从他进大学以来，他的英语提高了很多。
用before的话，主句应用过去时：Before he entered university, he studied in a high school for three years.
希望对你有帮助
答
after和before如果置于句首,有两种情况,一是充当介词角色,它们后面接的是动名词,即动词的ing形式；二是作为连词,引导的是从句,后面的主句应该用一般过去式.