英语34.I didn’t know when they________ again.34.I didn’t know when they________ again.A.came B.were coming C.had come D.had been coming为什么

英语34.I didn’t know when they________ again.
34.I didn’t know when they________ again.
A.came B.were coming C.had come D.had been coming
为什么

B
come这个短暂性动词的现在分词可以表示将来.
这里的were coming=were goint to come.
(我不知道他们什么时候会再来的）
“再来”是相对"知道"之后的,所以用过去将来时.