It is ____ asking Tom for help, for he is always the last to help others.
| A．useful | B．helpless | C．helpful | D．useless |
Water can absorb and __________ a lot of heat without big changes in temperature, thus creating a stable environment.
| A．give in | B．give up |
| C．give off | D．give away |
He can't go traveling very often as his work __________ almost all his time.
| A．takes away | B．takes in |
| C．takes over | D．takes up |
If he fails again, he will __________ us all __________ with him.
| A．drag; down | B．drag; in | C．drag; out | D．drag; up |
We had an anxious couple of weeks, __________ for the results of the experiment.
| A．wait | B．to be waiting |
| C．waited | D．waiting |
__________ such heavy pollution already, it may now be too late to clean up the river.
| A．Having suffered | B．Suffering |
| C．To suffer | D．Suffered |