活塞与气缸之间的配合间隙分布不均,运转时(),破坏油膜产生拉缸。
A.敲
B.燃气下窜
C.发生粘着
D.润滑不良
参考答案:A
Happily for the boy's parents, he is working harder and harder to________ his lost time.[ ]
A. make up for
B. catch up with
C. make use of
D. keep up with
镜检可见两种类型的腺毛及非腺毛的药材是()
A.西红花
B.红花
C.丁香
D.菊花
E.金银花