. It is pretty well understood ________ controls the flow of carbon dioxide in and out the atmosphere today.
| A．that | B．that what | C．what | D．how |
At a beach or a swimming pool a lifeguard is a person who is responsible for __________ other swimmers and protecting them from accidents.
| A．turning to | B．watching over | C．watching out | D．digging out |
The factory produces half a million pairs of shoes every year, 80% are sold abroad.
| A．of which | B．which of | C．of them | D．of that |
Her valuable advice ________ to be taken, or you will suffer more loss.
| A．deserves | B．survives | C．serves | D．proves |
—Ouch! You hurt me!
—I am sorry. But I any harm. Ito drive a rat out.
| A．didn’t mean; tried | B．don’t mean; am trying |
| C．haven’t meant; tried | D．didn’t mean; was trying |
—Did Jenny clean her house yesterday?
—She _______ because she was not quite herself.
| A．hadn’t cleaned it | B．had it cleaned | C．hasn’t cleaned it | D．has it cleaned |