Carbon dioxide，which makes a________between us and the sun，prevents heat from getting out of the atmosphere easily，so the earth is becoming warmer.
| A．difference | B．comparison |
| C．connection | D．barrier |
Tom had been studying French hard for nearly three yearshe mastered it．
| A．after | B．when | C．since | D．before |
---That must have been a terrible experience．
---Yeah．Iin the damaged car，unable to move．
| A．was stuck | B．have been stuck | C．am stuck | D．had been stuck． |
according to the instructions，the medicine will work for your headache．
| A．To take | B．Taking | C．Taken | D．Take |
As Mrs Roosevelt put ，I'd rather light a candle than complain about the darkness．
| A．it | B．that | C．this | D．them |
We can go on Tuesday or Friday，you preler.
| A．whenever | B．however | C．whatever | D．whichever |