1.It is the museum ______ I visited last week.2This the museum ______ I visited last week.

1.It is the museum ______ I visited last week.2This the museum ______ I visited last week.
A.where B.in which C.which D.that(上面两个题都是在这里面选,而且请详细说明原因）
补充：
3.We have 15 minutes left.(这个句中的“left“有何含义?）