滚动轴承一般由内圈、外圈、滚动件和保持架组成。内外圈上有滚道,当滚动时,滚动体将沿着滚道滚动。保持架的作用是把滚动件均匀的隔开。
A campus emergency ______ occur at any time of the day or night, weekend, or holiday, with little or no warning.
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