变频制冷压缩机高转速运转时()。
A.不用考虑任何问题
B.要考虑泄漏量增大的问题
C.要考虑润滑油量减小的问题
D.要考虑气阀流动阻力增大的问题
参考答案:D
Tom likes _____ to the movies with his friends and _____ sports. [ ]
A. going; playing
B. go; play
C. going; play
D. go; playing
活塞环的功用是什么?