安全控制的主要对象是(),有人把安全控制也称为安全风险控制。
A.监理人员
B.危险源
C.机械设备
D.安全制度
参考答案:B
The author of the report is well _____ with the problems in the hospital because he has been working there for many years.
A.acquainted
B.informed
C.known
D.advised
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