红外光谱图中,1650~1900cm-1处具有强吸收峰的基团是
A.甲基
B.羰基
C.羟基
D.氰基
E.苯环
参考答案:B
Eating________vegetables and less meat can help you to keep in good ________
A.more; health
B.much; health
C.more; healthy
D.many; healthy
下列哪个大洲既位于北半球又位于西半球[ ]
A.亚洲
B.非洲
C.北美洲
D.南美洲