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问题 选择题

下列物质属于纯净物的是（　　）

A．硬水

B．水

C．钢

D．煤

答案

A、硬水中含有水、可溶性钙镁化合物等多种物质，属于混合物．故错误；

B、水中只含有一种物质，属于纯净物．故正确．

C、钢中含有铁、碳等多种物质，属于混合物，故错误；

D、煤中含有碳、硫、无机矿物质等多种物质，属于混合物，故错误．

故选B．

单项选择题

A community nurse is performing a physical assessment on an 18-month-old child. Which of the following would be best

A. Carry out the assessment from head to toe.
B. Assess motor function by having the child run and walk.
C. Have the mother hold the toddler on her lap.
D. Assess the respiratory and cardiac systems first.
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单项选择题

I would have accompanied you to the cinema yesterday, but I （） no time.

A. had had

B. could have had

C. might have had

D. had
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