-Why does the lake smell terrible?
-Because large quantities of water .
| A．is being polluted | B．have been polluted |
| C．is polluted | D．has been polluted |
It is still unclear ______ the little boy got the CD player to work．
| A．where | B．what | C．that | D．how |
—Ring me at six tomorrow morning, will you?
—Why that early? I ____.
| A．will be sleeping | B．will sleep |
| C．have slept | D．have been sleeping |
She tried two different methods, yet ______ of them seemed to work very well．
| A．neither | B．none | C．each | D．both |
—What about ______ lecture you attended yesterday?
—To tell the truth, it was too boring．I can’t stand ______ lecture like that．
| A．a; the | B．the; a | C．the; 不填 | D．the; the |
He raised his voice, ______ we still couldn’t hear anything．
| A．so | B．or | C．but | D．as |