当孔板阀正常工作时,滑阀(),下阀腔压力与上游管内压力相等,上阀腔内压力()大气压。
A.打开,大于
B.关闭,等于
C.50%阀位,小于
D.自由开关,大于
参考答案:B
A firm from New Zealand has revealed a set of robotic legs which they claim will soon
allow _______ wheel chair - bound people to walk again.[ ]
A. originally
B. previously
C. properly
D. primarily
在配电线路放线时,采用放线滑轮可达到()又不会()的目的。