They want to make _____ clear to the public that they are doing an important and necessary job.
| A．that | B．this | C．it | D．one |
Drivers must stop when the traffic lights _____ red．
| A．turn | B．will turn |
| C．turned | D．were turning |
There was an excited expression ______ his face when he heard the good news．
| A．of | B．on |
| C．at | D．over |
Milk will turn sour soon on hot days ______ it is stored in the refrigerator．
| A．since | B．until |
| C．because | D．unless |
You'd better not ride the bicycle on snowy days; you ______ fall．
| A．must | B．might |
| C．have to | D．ought to |
—Hi, Jack．You look a bit fat now．
—Yes, I ______ five pounds recently．
| A．am putting on | B．will put on |
| C．have put on | D．had put on |