________ has been mentioned above，continued chairman after he took a sip of coffee，________ the project must be carried out before spring flood comes.
| A．As；that | B．That；which |
| C．This；which | D．It；that |
It is so heavy a box _____ no one can move.
| A．that. | B．which. | C．as. | D．what. |
—Why does the lake smell terrible?
—Because large quantities of water _____.
| A．have polluted. | B．is being polluted. |
| C．has been polluted. | D．have been polluted. |
Sarah hopes to become a friend of_______ shares her interests.
| A．anyone | B．whomever | C．whoever | D．no matter who |
After years of overwork, my father’s health ____ and he had to retire from business.
| A．broke out. | B．broke up. | C．broke down. | D．broke off. |
_____ you may have, you should gather your courage to face the challenge.
| A．However serious a problem. | B．What a serious problem. |
| C．However a serious problem. | D．What serious a problem. |