____the teacher came into the classroom,they were arguing

题目

____the teacher came into the classroom,they were arguing
before after until while as 选

答案

应该是when或as,虽然没有when这个选项.因为when和as后的从句可以是一般过去时也可以是过去进行时.而while后面一般是过去进行时.before和until和after一般和完成时用在一起.要用过去完成时.所以选as.