【单选题】△h、r△hc分别代表有效汽蚀余量、必需汽蚀余量、临界汽蚀余量,为了泵能避免发生汽蚀,要求____。
C.
△ha≥lOO%△hC(两者差值不小于0、5 m)
D.
△ha≥11O%△hr(两者差值不小于0、5 m)
【单选题】He is a student of ____.
【单选题】对高压钢瓶下列哪些是不正确的。()
D.
无论新旧,只要有出厂合格证就证明可正常可用。
【单选题】He is a student of _______ international middle school. [ ]
【判断题】国际贸易惯例像法律一样有强制性,例如UCP600.
【简答题】The point is whether we ought to recommend him.
【单选题】( ),又称契约,是两个或两个以上的当事人以发生、变更或消灭民事法律关系为目的而达成的协议。
【简答题】Bob is from London. His father has a shop there and his mother works on a farm. He is a student of Grade Seven. His father drives him to school every day. So he is never late for school and his teache...