The government has to close those small factories to prevent the water of the river ______.
| A．polluting | B．from polluting | C．being polluted | D．polluted |
I have been keeping the portrait _____ I can see it every day, as it always reminds me of my childhood in Paris.
| A．since | B．where | C．as | D．if |
_____earth scientists understand how and why earthquakes happen, forecasts are usually inaccurate.
| A．As | B．While | C．Because | D．If |
Mr. Smith wanted to buy the house and he told me that ____the house cost，it would be worth it.
| A．however | B．how much | C．whatever | D．what |
I was so excited last night that it was a long time _____I got to sleep.
| A．that | B．since | C．before | D．when |
He finally won the general election because many of his promises were quite popular _____ the voters.
| A．for | B．in | C．to | D．with |