有两瓶失去标签的无色溶液，一瓶是盐酸，另一瓶是碳酸钠溶液.欲

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问题选择题

有两瓶失去标签的无色溶液，一瓶是盐酸，另一瓶是碳酸钠溶液.欲将其鉴别出来，最经济的方法是

A．加入BaCl₂溶液

B．加入石蕊试液

C．加入NaOH溶液和酚酞的混合溶液

D．无需任何试剂

答案

答案：D

填空题

根据句意，用括号中所给单词的适当形式填空。

1. He'd like to buy a present for his sister's _______ (twelve) birthday.

2. We must pay attention to_______(tell) the differences between them.

3. David is the chairperson of the _______(student) Union.

4. We held the 29th Olympic Games _______(sucess)

5.You shouldn't worry about _______(not have ) breakfast.

6. How many _______(operate) do you perform every year?

7. I_______(stay) at home and sleep all day if there is no school tomorrow.

8. The man was badly hurt in the accident and he_______(send) to hospital immediately.

判断题

时间参数主要包括流水节拍、流水步距与施工段数。