球型阀与闸阀比较，其优点是局部阻力小，开启和关闭力小。
参考答案：错
British Prince William (威廉王子) and Kate _________ for nearly two months. [ ]
A. married
B. have married
C. have been married
D. have got married
下列属于软体动物的是（ ）
A．蚯蚓
B．蛔虫
C．河蚌
D．草履虫
