This printer is of good quality. If it _______ break down within the first year, we would repair it at our expense.
| A．would | B．should | C．could | D．might |
We must take steps to prevent the __________ world population.
| A．exploded | B．exploding | C．explosion | D．explosively |
The amount of money that he saved reached _________ 30000 dollars.
| A．as many as | B．as much as | C．as high as | D．as far as |
It is pretty well understood_______controls the flow of carbon dioxide in and out of the atmosphere today．
| A．that | B．when | C．what | D．which |
Mary got into acting purely _____________.
| A．accidental | B．accident | C．by accident | D．with accident |
It is no use thinking about your ________ youth.
| A．gone | B．lost | C．missed | D．losing |