牙釉质中的有机物成分主要是（）。
A.蛋白质
B.脂肪
C.脂类
D.维生素
E.糖类
参考答案：A, C
— The weatherman on the news said it might rain later on this afternoon.
— Well, I ____ take my umbrella along with me today. [ ]
A. can
B. may
C. could
D. must
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