一桶水倒去一半，此时桶中水的质量______，水的体积______，密度____

(1)年逾花甲 (2)豆蔻年华 (3)而立之年 (4)两小无猜 (5)知命之年

A．4—2—3—5—1

B．4—2—3—1—5

C．3—1—4—2—5

D．2—1—4—3—5

最简单的液力变矩器由（）、（）和（）三个工作轮和壳体组成。当涡轮转速（）到一定程度时，为了减少导轮对液流的阻力，在导轮上加装了单向离合器（也称自由轮）机构。

腰椎麻醉时常合用麻黄碱，其目的是防止局部麻醉药

A．抑制呼吸
B．引起心律失常
C．扩散吸收
D．降低血压
E．局部麻醉作用过快消失

A definite advantage of using water as a fire extiguishing agent is its characteristic of（）.

A.alternate expansion and contraction as water in a liquid state becomes a vapor

B.absorption of smoke and gases as water is converted from a liquid to a vapor

C.rapid contraction as water is converted from a liquid to a vapor

D.rapid expansion as water absorbs heat and changes to steam

图示外伸梁，A截面的剪力为：（）

A.A

B.B

C.C

D.D