棉纤维含糖的种类按糖分的来源分为()。
A、还原糖
B、内源糖
C、非还原糖
D、外源糖
参考答案:B, D
曲线y=2x2在点P(1,2)处的切线方程是 [ ]
A.4x﹣y﹣2=0
B.4x+y﹣2=0
C.4x+y+2=0
D.4x﹣y+2=0
The disabled people feel grateful _______ you ________ your help.
A.for; to
B.to; for
C.for; for
D.to; to