He kept his eyes and stayed where he was.
| A．shut | B．to be shut |
| C．shutting | D．to shut |
The bell __ the end of the period rang, __our heated discussion.
| A．indicating, interrupting | B．indicated, interrupting |
| C．indicating, interrupted | D．indicated, interrupted |
_______cloning human embryos is not legal in many countries, some scientists are already pushing ahead with research in order to produce a cloned human baby.
| A．While | B．When | C．Since | D．if only |
________ the programme, they have to stay there for another two weeks.
A Not completing B Not completed
C Not having completed D Having not completed
When the boss came in, these workers pretended to________ carefully.
| A．working | B．be working |
| C．work | D．have been working |
People often have this belief ___development is bad for the environment, but this does not have to be true.
A which B whose C that D when