It _________ be the postman at the door. It’s only six o’clock.
| A．mustn’t |
| B．can’t |
| C．won’t |
| D．needn’t |
.What________ pity that you couldn’t be there to receive ________ prize!
| A．a, a | B．the, a | C．the, the | D．a, the |
.Water, which seems to be so simple and common, is ______ makes life possible.
| A．that | B．which | C．what | D．where |
The number of students in this college _____ by 10% every year.
| A．rises | B．lifts | C．raises | D．arises |
.______ the beginning of the 19th century did scientists know that all matter is made up of 
atoms.
| A．At | B．By | C．Up to | D．Not until |
Many people believe that _______ will takes years to develop a car that does not pollute the air.
| A．it | B．that | C．there | D．this |