1.We should protect plants,________?(反义疑问句）

1.We should protect plants,________?(反义疑问句）
2.-Could you tell me (where they have been)?I must find them.
-Sorry,but they were in the classroom just now.
(请问 括号里的 为什么不能用 where they have gone?)
3.If I knew the answer to the maths question,I (told you) soon
(请问 括号里为什么不填 will tell you?)
wachief 我也是你那样想的 到底是怎样的呢。