－Many boy students think math is ______ English.
－I agree. I’m weak in English.
| A．much difficult than | B．so difficult as |
| C．less difficult than | D．more difficult than |
I enjoy fresh air so I always let the window open ________ it is really cold.
| A．unless | B．when | C．if | D．since |
We will have no water to drink ________ we don't protect the earth.
| A．until | B．before | C．though | D．if |
—You bought the car about ten years ago?
—Yes.________ it's old，it still runs well.
| A．Because | B．Since | C．Although | D．But |
Mark isn't coming to the concert ________________ he has got too much work to do.
| A．so | B．until | C．although | D．because |
-When will you go back to your hometown? - _______.
| A．Until the work is finished |
| B．Not until the work is finished |
| C．After the work will be finished |
| D．As soon as the work will be finished |