The place ________ interested me most was the Children’s Palace.
A, which B, where C, what D, in which
I just wonder ________ that makes him so excited.
| A．why it does | B．what he does |
| C．how it is | D．what it is |
________ caused the accident is still a complete mystery.
| A．What | B．That | C．How | D．Where |
I’m afraid he’s more of a talker than a doer，which is ________ he never finishes anything. (2011·山东，26)
| A．that | B．when |
| C．where | D．why |
Scientists study ________ human brains work to make computers. (2012·四川，17)
| A．when | B．how |
| C．that | D．whether |
It suddenly occurred to him________he had left his keys in the office. (2012·江西，25)
| A．whether | B．where |
| C．which | D．that |