几道高中英语题（有关定语从句）
1.Is the lab__the foreigners visited yesterday.
A.that B.where
C.in which D.the one
题目的正确答案是D,但为什么不能用A呢,难道the lab不是先行词吗?that不能作宾语吗?顺便告诉我一下这类问句怎么做..谢了
2.The accident happened ___they once worked.
A.in which B.at which
C.whereD.the palace in which
正确答案是C,但为什么A不可以呢,in which 不就是where 的意思么?
3.有关the reason的定语从句,为什么有时候用why ,有时候却用that?