Can you imagine what problem may ______ when human beings are cloned?
| A．raise | B．cause |
| C．arise | D．lead |
— Dad, would you please buy some strawberries for me? I love them.
— I'd like to, but they are not _____ in winter.
| A．accustomed | B．convenient |
| C．casual | D．Available |
—Do you know where David is? I couldn't find him anywhere.
—Well, he ______ have gone far—his coat's still here.
| A．shouldn't | B．mustn't | C．can't | D．wouldn't |
She is getting better, but it will be some time ______ she is completely well.
| A．that | B．since | C．when | D．Before |
The computer centre, ______ last year, is very popular among the students in this school.
| A．open | B．opening |
| C．having opened | D．Opened |
______ in thought, he almost ran into the car in front of him.
| A．Losing | B．Having lost |
| C．Lost | D．To lose |