Not everyone has realized what_______ important part the balance of________ nature plays in their life.
| A．an；the | B．/；the | C．an；/ | D．the；/ |
It is exactly _____we behave _____has changed the world.
| A．which; that | B．how; that | C．how; what | D．what; that |
—I can’t find Xiao Ping, where did you see him this morning?
—It was in the library______ he studied．
| A．that | B．where | C．which | D．the one |
—________ matters to do the job well —what you are or where you come from?
—Neither. It depends on whether you put your heart into it.
| A．Which is it that | B．What it is that |
| C．Which it is that | D．What is it which |
----How unhappy your roommate looks!
----Yes，but he’s not willing to tell me what it is____ is troubling him.
| A．what | B．which | C．as | D．that |
It was along the Mississippi River _______ Mark Twain spent much of his childhood.
| A．how | B．which | C．that | D．where |