It is suggested that some skills teachers ________ to teach the children in these mountainous areas .
| A．must be sent | B．be sent | C．should send | D．should send for |
(2012年重庆联合诊断性考试)It is rather difficult to make friends with him，but his friendship，________，is more true than any other's.
| A．once gained |
| B．when to gain |
| C．after gaining |
| D．while gaining |
(2012年石家庄质量检测)Once ________，such a chance might never come again.
| A．losing |
| B．lost |
| C．to bo lost |
| D．having lost |
(2012年江苏南通九校联考)When ________different cultures，we often pay attention only to the differences without noticing many similarities.
| A．compared |
| B．being compared |
| C．comparing |
| D．having compared |
(2012年潍坊市高三质量检测)A harmonious society is like a symphony or orchestra－
each person contributes a small sound，but when________with other sounds，it becomes beautiful music.
| A．combining |
| B．being combined |
| C．combined |
| D．to be combined |
(2012年河南长葛高三月考，29)He made another wonderful discovery，________of great importance to science.
| A．which I think is |
| B．which I think it is |
| C．which I think |
| D．I think which is |