The CDC says that even fully _______ travelers risk getting and spreading COVID-19 ______in Japan
A. variant
B. vaccinate
C. variants
D. vaccinated
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It’s easy to forget that the ___ for this have been one of the ____ struggles for/in human history.
Today 7 in 10 people on earth can ______ having _______ in their homes
______ that _____ water thrived
( )能很好地承受径向载荷与单向轴向载荷的综合作用。
A. 深沟球轴承
B. 角接触球轴承
C. 推力球轴承
D. 圆柱滚子轴承
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