题目内容

Complete the sentences with the proper form of the given verbs.1. I am looking forward to _______________ her soon. (meet)2. He put off _______________ a decision till he had more information. (make)3. He left the restaurant without _______________ his bill. (pay)4. Is there any chance of _______________ his mind? (change)5. I gave up _______________ to persuade him to continue with his studies. (try)6. If no one helps him, he may end up _______________ a beggar. (be)

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名词解释:变焦距镜头。

拍摄人面部表情,起到借景抒情效果的是柔焦镜头。

A. 对
B. 错

影响缓冲能力的主要因素是()

A. 缓冲溶液的pH值与缓冲比
B. pKa与缓冲比
C. 总浓度与缓冲比
D. 缓冲液的总浓度与pH值

今有三种溶液分别由两组分组成:(a) 0.10 mol/L HCl-0.20 mol/L NaAc溶液(b) 0.20 mol/L HAc-0.10 mol/L NaOH溶液(c) 0.10 mol/L HAc-0.10 mol/L NaAc溶液则三种溶液pH的大小关系是[已知pKa(HAc)= 4.74]()

A. a B. a = b C. a = b>c
D. a = b = c

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