非金属垫片、铜垫片如何进行脱脂?
参考答案:
非金属垫片及填料可在溶剂中浸泡15~20min,然后悬挂职在通风处吹干,直至无溶剂气味为止。铜、铝垫片退火后可不再进行脱脂。
什么是个人诚信体系?
—Hi, Susan, I didn’t see you at the party.
—Oh, I ______for an English test.[ ]
A. studied
B. am studying
C. was studying