题目内容

通常情况下,紫外光区与可见光区的波长范围分别是

A. 200nm-400nm; 400nm-800nm
B. 200nm-400nm; 400nm-600nm
C. 100nm-360nm; 400nm-800nm
D. 100nm-360nm; 360nm-600nm

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当吸光度A=0时,则透光率T/%=()

A. 50
B. 20
C. 1
D. 100

--- Tom graduated from college at a very young age.--- Oh, he ______ have been a very smart boy then.

A. could
B. should
C. might
D. must

--- I don't mind telling you what I know.--- You ______. I'm not asking you for it.

A. mustn't
B. may not
C. can't
D. needn't

--- Excuse me, but I want to use your computer to type a report. --- You _____have my computer if you don't take care of it.

A. shan't
B. might not
C. needn't
D. shouldn't

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