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问题 选择题

下列实验操作正确的是[ ]

A．制乙酸酯时，迅速将乙醇注入浓硫酸中

B．手上沾有少量苯酚，立即用氢氧化钠溶液清洗

C．少量浓硫酸沾在皮肤上，立即用大量清水冲洗

D．用氢气还原氧化铜时，加热一段时间后再通入氢气

答案

答案：C

单项选择题

Man: Have you run up against any problems in getting your passport renewedWoman: I haven't started the plan yet.Question: What do know from the conversation

A．The woman doesn't think it a problem to get her passport renewed.

B．The woman has difficulty renewing her passport.

C．The woman hasn't renewed her passport yet.

D．The woman's passport is still valid.
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单项选择题

下列物质具有清除体内自由基的作用，例外的是（）

A.维生素E

B.维生素C

C.β－胡萝卜素

D.钙、磷E.硒
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