题目内容

造成我国野生生物资源减少的主要原因是( )

A. 生存斗争过于激烈
B. 物种退化
C. 自然条件的变化
D. 生存环境的改变和破坏

查看答案
更多问题

Whatcausesspeedreductionincylindercushioning?

A. oilflowthroughasmallhole
B. backpressurecreatedinthesystem
C. bothA.andB.
D. noneoftheabove

Whyarehydrauliccylinderscushioned?

A. cushioningdeceleratesthepistonofacylinder
B. stressandvibrationscanbereduced
C. bothA.andB.
D. noneoftheabove

Cylinderendcushioningdecreasespistonspeedbytheendofthepistonmotion.

A. 对
B. 错

Cylinderendcushioning does not prevent piston motion atthebeginningof a stroke.

A. 对
B. 错

答案查题题库