The children，__________ had played the whole day long, were worn out.
| A．all of what | B．all of which |
| C．all of them | D．all of whom |
Suddenly it _________ to me that I should report the accident to the police.
| A．happened | B．struck | C．occurred | D．hit |
The following chapters provide step-by-step instructions for practical _______ of genetic (基因)engineering to agriculture.
| A．applications | B．organization | C．expression | D．attention |
What a moving _____to see so many people offer help to these in danger!
| A．sight | B．scene | C．view | D．scenery |
—Please let me know where David is. I couldn’t find him anywhere.
—Well, he _____have gone far—his coat’s still here.
| A．shouldn’t | B．mustn’t | C．can’t | D．wouldn’t |
He should have come here earlier, but he hasn’t _____yet.
| A．turned in | B．turned up | C．turned on | D．turned out |