问题描述：
In order to eat safely,I think we _____ make some food by ourselves instead of buying some.[ ]A.used to
B.prefer to
C.had better
D.are supposed to
选C还是D，为什么，为什么不选另一个？
B.prefer to
C.had better
D.are supposed to
选C还是D，为什么，为什么不选另一个？
问题解答：
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