试题与答案

重金属检查法中,若以硫代乙酰胺做显色剂,溶液最适pH是A.3~3.5 B.4~4.5

题型:单项选择题

题目:

重金属检查法中,若以硫代乙酰胺做显色剂,溶液最适pH是

A.3~3.5

B.4~4.5

C.5~5.5

D.6~6.5

E.7~7.5

答案:

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63.The most widespread problem in applying oneself to study is ________.

A. changing from one subject to another

B. the failure to keep to a set timetable of work

C. the unwillingness to follow a systematic plan

D. working on a subject only when one feels like it

64.Which of the following is true ?

A. Many students are not interested in using a self-controlled timetable.

B. Many students don’t like being told to study to a fixed timetable.

C. Most people over 25 years of age don’t work to a set timetable.

D. Tough-minded people agree that good work is done naturally.

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A. when they have the energy                                               B. when they are in the mood

C. when they feel fit                                                        D. when they find conditions suitable

66.A suitable title for the passage might be ________.

A. Attitudes to Study                                                      B. A study Plan

C. The Difficulties of Studying                             D. Study and Self-discipline

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