This is the hotel ________ last month.
| A．which they stayed | B．at that they stayed |
| C．where they stayed at | D．where they stayed |
.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 |
They have been woking on this project for one month. It seems they need ________ month to finish it.
| A．more | B．other | C．another | D．the other |