下列对细胞分裂的相关叙述中，正确的是（ ）

阅读下面短文，掌握大意，然后从21-40各题所给的四个选项（A、B、C和D）中，选出最佳答案。

        My parents got divorced when I was one year old. I've heard from family that it was because my father was 1， but I was too little to remember and he was never violent  2I was growing up. My father is an alcoholic. He was 3once when I was a teenager for three years then had another divorce. I'm his4child. My mother has been married and divorced three times, and all of her 5were abusive. I'm the oldest of five half­ siblings. My first step­father was  6violent with my mother regularly, they were married when I was 2 and 7when I was 8. My second step­father never fought with my mother，8was verbally (言语)abusive with my two oldest younger brothers and myself and also  9me when I was 17. They were married when I was 11 and 10divorce proceedings last year when I was 22. The divorce was just finalized last month. I'm sure I don't have to 11detail about the emotional influences of growing up in this12. I do find that it has made it difficult for me to 13the pattern for my own life. I find myself using escapism(逃避现实) when 14gets too hard, just like my mother did. I find myself latching(锁定) on to 15men with a co­dependent loyal. My father's drug and alcohol use has also  16my decisions. All of the people I have been in a  17relationship with have a drug addiction of some sort. I've never been 18to drugs, though. Only people. In spite of all of this, I am committed to 19these generational problems that have been a part of my family history 20since my great­ grandparents.

【查阅资料】白磷的着火点为40℃．

【提出问题】氧气体积约占空气总体积的多少？

【实验准备】锥形瓶内空气体积为230mL，注射器中水的体积为50mL，该装置气密性良好．

【实验探究】装入药品，按图所示连接好仪器，夹紧弹簧夹．先将锥形瓶底部放入热水中，白磷很快被引燃，然后将锥形瓶从热水中取出．

【现象分析】