通过流体对阀芯的作用把阀芯分为哪两种（）
A.流开式阀芯
B.流闭式阀芯
C.自保持阀芯
D.反作用阀芯
参考答案：A, B
As we all know, Lost in Thailand is a very successful movie, the cost of ______ is only 30 million yuan.
A．which
B．that
C．whose
D．whom
与土地初始登记相比，土地变更登记具有( )等特点。
A．分散性和个别性
B．经常性和及时性
C．集中性和统一性
D．连带性
