________hard before, Tom is afraid of failing in the exam.
| A．Having been worked | B．Not to have worked |
| C．Having never worked | D．Never have worked |
The collapse of the World Trade Centre has put US economy in a difficult___________.
| A．occasion | B．case | C．situation | D．background |
More and more people choose to shop in a supermarket as it offers a great _______of goods.
| A．variety | B．mixture | C．extension | D．combination |
Life is tough in the city. In order to lose their ，some people drink alcohol.
| A．temper | B．mood | C．consciousness | D．pressures |
One of the consequences of our planet's being warming up is a（n）_______ in the number of natural disasters.
| A．result | B．account | C．reason | D．increase |
“I don't think it's my ________that the TV blew up. I just turned it on，that's all，”said the boy.
| A．error | B．mistake | C．fault | D．duty |