821.Children under 12 years of age in that country _______ be under adult's supervision when in a public library.
A.must
B.may
C.can
D.need
822.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