I think every student ____in the classroom witnessed the strange chemical changeA.remainingB.leavingC.to remain D.to leave为什么选A?

I think every student ____in the classroom witnessed the strange chemical changeA.remainingB.leavingC.to remain D.to leave为什么选A?
I think every student ____in the classroom witnessed the strange chemical change
A.remainingB.leavingC.to remain D.to leave
为什么选A?

I think every student ____in the classroom witnessed the strange chemical changeA.remainingB.leavingC.to remain D.to leave为什么选A?
这是一个带定语从句的complex.现在分词remaining表主动.用leave就该用left了.因为leave相当于not take,所以从句意逻辑看来要用过去分词表被动.后面两个用不定式明显错误.

A.remaining 在场的
B.leaving 正在离开的
C.to remain 即将留下的
D.to leave 即将离开的
b，c，d意思都不靠谱

选A
可理解成定语从句“every student who remained in the classroom”省略了关系代词who,动词要用非谓语形式。