A new technique ____ out, the yields (收成) increased by 20% .
| A．having working | B．having been working |
| C．has worked | D．had been worked |
You must try some of her home-made wine and it’s quite ____ experience! I know from ____ experience it is very good.
| A．the; the | B．an; an | C．an; / | D．/;an |
There ____ a terrible accident then, ____ three passengers were killed and twenty were injured as well.
| A．was occurred; which | B．was occurred; in which |
| C．occurred; which | D．occurred; in which |
In yesterday’s newspaper, it was reported that great damage ____by the flood.
| A．has been done | B．had been done | C．has done | D．had done |
It’s reported that the United States uses ______ energy as the whole of Europe.
| A．as twice | B．twice much | C．twice much as | D．twice as much |
The experiment shows that proper amounts of exercise, if ______ regularly, can improve our health.
| A．being carried out | B．carrying out | C．carried out | D．to carry out |