题目

如图有关图中细胞生命历程的叙述正确的是（ ） A . 癌变前后，细胞内的基因相同 B . 细胞中的水分减少、色素积累是细胞衰老的特征 C . 细胞的分化只能发生在胚胎发育时期 D . 都始终存在核膜、核仁等结构 答案：B从方框中选择最佳选项完成对话，有两项多余。 A. My parents got angry with me.  B. Maybe I can help you with it.  C. The teacher said I could do better.  D. What’s the matter with you?  E. I really had a difficult time studying math.  F. Why not go home and say sorry to your parents?  G. That’s too bad.  A:  Hello, Mark! You look unhappy.    1   B:  I argued with my parents last night.  A:  Why did you do that?  B:  I got my report card yesterday.  I didn’t do well in math.    2   A:    3   You should work harder at math.  B:  I know, but I find it really difficult and I really don’t know how to improve it.  A:    4    B:  That’s great.   Thanks a lot.  A:  You’re welcome.    5    B:  I will.