核酸变性后，可发生的效应是（）
A.分子量增大
B.增色效应
C.失去对紫外线的吸收能力
D.最大吸收波长发生转移
E.溶液黏度增加
参考答案：B
----Help yourself to some apples and grapes, please. ----_____.
A．Yes, of course
B．Thank you
C．That’s right
D．Yes, I will.
（2014届江西省重点中学盟校高三第二次联考英语试卷）27. She cared more about her students than her own health. That’s why two years passed _____ she was treated for breast cancer.
A．since
B．before
C．after
D．until
