下列是有关细胞分裂的问题。图1表示细胞分裂的不同时期与每条染

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下列是有关细胞分裂的问题。图1表示细胞分裂的不同时期与每条染色体DNA含量变化的关系；图2表示处于细胞分裂不同时期的细胞图象，请据图回答：

(1)图1中AB段形成的原因是________，该过程发生于细胞分裂间期的________期，图1中CD段形成的原因是________。

(2)图2中________细胞处于图1中的BC段，图2中________细胞处于图1中的DE段。

(3)就图2分析可知，该细胞含有________条染色单体，染色体数与DNA分子数之比为________，该细胞处于________分裂的________期，其产生的子细胞名称为________。

答案

(1)DNA复制(或染色体复制) S 着丝点分裂

(2)乙、丙甲

(3)8 1:2 减数第一次后次级卵母细胞和第一极体

完形填空

My father brought home a sailboat when I was ten, and almost each Sunday in summers we would go sailing. Dad was quite skilled in sailing, but not good at ___36___. As for me, I ___37___ both before twelve because of living close to Lake Ontario.
The last time Dad and I set sail together is really ___ 38___. It was a perfect weekend after I graduated from university. I came home and ___39___Dad to go sailing. Out we set soon on the ___40___lake. Dad hadn’t sailed for years, but everything ___41___well with the tiller（舵柄）in his hands.
When we were in the middle of the lake, a ___ 42___ wind came all of a sudden. The boat was hit ___43___. Dad was always at his best in any___44___, but at this moment he___45___.
"John!___46___!" he shouted in a trembling voice, with the tiller still in his hands.
In my memory he could fix any___ 47___. He was the one I always___48___for strength and security. Before I could respond, a___ 49___ of water got into the boat. I rushed to the tiller ___50___it was too late. Another huge wall of water ___ 51___the boat in a minute. We were thrown into the water, and Dad was struggling aimlessly. At that moment, I felt fiercely ___52___of him.
I swam to Dad ___ 53___and assisted him in climbing onto the hull（船壳）of the boat. Upon sitting on the hull, Dad was a little awkward about his flash of ___ 54___. "It's all right, Dad. We are safe now," I comforted him.
That was the first time Dad had counted on me in a moment of emergency. More importantly, I found it was my turn to start___55___for my father.

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选择题

世界银行、国际货币基金组织和关贸总协定成为二战后支撑世界经贸关系的三大支柱，这一局面的形成:①确立了英国的主导地位 ②顺应了经济全球化趋势 ③反映了二战后世界经济向着体系化、制度化方向发展 ④消除了国际贸易障碍

A．①②

B．②③

C．①③

D．②④

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