影响CVP的病理因素包括（）
A.房颤
B.血管升压素分泌升高
C.PEEP
D.心包填塞
E.右心衰竭
参考答案：A, D, E
现代化的精密机床的液压系统常用（）泵。
A、齿轮
B、叶片
C、柱塞
D、螺杆
Scientists estimate that about 530,000 other objects, too small to detect with radar, () the Earth too.
A. being circled
B. are circling
C. are to be circling
D. are being circled
