Scientists from different countries are trying to_______ a good way to solve the energy problem.
| A．keep up with | B．come up with | C．catch up with | D．meet up with |
We are from China and we _______ Chinese.
| A．say | B．talk | C．speak | D．tell |
Some students are so ______ that they often make mistakes in their homework.
| A．carful | B．serious | C．careless | D．successful |
__ we are young, we can still do something to help protect the environment.
| A．If | B．Since | C．Because | D．Though |
--- Jimmy, don’t put this pair of trousers on the sofa.
--- Sorry, mum. I will _____________ right now.
| A．take it away | B．take them away |
| C．knock it off | D．knock them off |
---You were out when I went to your house this morning.
---Oh, I _______ for a friend from England at the airport.
| A．was waiting | B．waited |
| C．am waiting | D．have waited |