the staffer said he did not know _____the meeting.a.when we started b.when will start c.when would start d.when to start答案及原因（详细）listen!helen is singing in the next room .it ____be helen,she is gone to beijing.a.can't

the staffer said he did not know _____the meeting.a.when we started b.when will start c.when would start d.when to start答案及原因（详细）listen!helen is singing in the next room .it ____be helen,she is gone to beijing.a.can't
the staffer said he did not know _____the meeting.
a.when we started b.when will start c.when would start d.when to start
答案及原因（详细）
listen!helen is singing in the next room .
it ____be helen,she is gone to beijing.
a.can't b.mustn't c.may d.should

the staffer said he did not know _____the meeting.a.when we started b.when will start c.when would start d.when to start答案及原因（详细）listen!helen is singing in the next room .it ____be helen,she is gone to beijing.a.can't
The staffer said he did not know _when we started_ the meeting.选A.
B显然错误；C项start应该在the meeting后面,而且也没有必要用过去将来时；D不定式表示将来的动作,不对.
It can't be helen.选A,表示“不可能”.