If the balance of nature is ____ , a series of problems will arise .
| A．disturbed | B．troubled | C．interrupted | D．confused |
A good listener takes part in the conversation，________ ideas and raising questions to keep the talk flowing.
| A．realizing | B．copying |
| C．offering | D．misunderstanding |
When the group discussion is nearing its end，make sure to ________ it with important points.
| A．conclude | B．lead | C．avoid | D．hold |
Try not to cough more than you can________since it may cause problems to your lungs.
| A．check | B．allow | C．stop | D．help |
Time is of no importance to great thoughts，________ are as fresh today as when they first passed through thinkers' minds ages ago.
| A．what | B．that | C．which | D．where |
Now there is just one point ________ I wish you to make quite clear.
| A．where | B．which | C．whether | D．when |