It's wellknown that the world economic situation will get worse________.[ ]

A. not if dealt carefully with

B. if not carefully dealt with

C. if dealt not carefully with

D. not if carefully dealt with

（）是由装在壳体内的一对浸在油液中的互相啮合的齿轮组成，一个是主动齿轮，另一个是从动齿轮，齿轮两端面靠端盖密封。

A.齿轮泵

B.叶片泵

C.柱塞泵

D.液压缸