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