Los Angeles Times reported that researchers may have found a way to ______ human life by changing certain genes, so that humans might expect to live twice as long.
| A．extend | B．preserve |
| C．multiply | D．transform |
You may catch up with others __________ you work a little harder.
| A．so long as | B．so far as | C．however | D．unless |
Without electricity human life __________ quite different today.
| A．is | B．will be | C．would have been | D．would be |
Gunpowder is generally believed __________ in ancient China.
| A．to have invented | B．being invented | C．to have been invented | D．having invented |
It was __________ great shock to the world that a French airplane got missing over __________ Atlantic Ocean on June 1st, 2009.
| A．a; ／ | B．the; the | C．a; the | D．/; the |
I feel nervous before the exam.
-- __________. It won’t be too difficult for you to pass.
| A．Take it easy | B．Never mind | C．Take your time | D．Don’t mention it |