如图表示人在生殖发育过程中染色体数目的变化．（1）A、B分别_爱下问搜题

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问题填空题

如图表示人在生殖发育过程中染色体数目的变化．

（1）A、B分别代表父母的体细胞，则染色体数均为______条．

（2）a和b分别是A、B产生的生殖细胞，则a和b分别叫做______、______．

（3）a和b相结合形成的C叫做______，其染色体数为______对．

答案

（1）正常人的体细胞染色体数目为23对，并有一定的形态和结构；a、b为该夫妇的体细胞，染色体数为23对，即46条．

（2）在形成生殖细胞的过程中，成对的染色体分开，每对染色体中的一条进入精子或卵细胞中，a和b分别是A、B产生的生殖细胞，则a和b分别叫做精子、卵细胞．

（3）在亲代的生殖细胞形成过程中，经过减数分裂，染色体彼此分离，男性产生两种类型的精子--含22+X染色体的精子和含22+Y染色体的精子．女性则只产一种含22+X染色体的卵细胞．受精时，如果是含22+X的精子与卵子结合，就产生具有44+XX的受精卵并发育成女性；如果是含22+Y的精子与卵子结合，就产生具有44+XY的受精卵并发育成为男性．因此通过受精作用形成受精卵，染色体又恢复为23对，23条来自母亲，23条来自父亲，故人的受精卵中染色体的数目是23对．

故答案为：

（1）46 （2）精子；卵细胞（3）受精卵；23

多项选择题

对于美式期权来说，有效期长的期权包含______。

A．有效期短的期权的所有的执行机会

B．买方行使期权的机会越少

C．买方行使期权的机会越多

D．有效期越长，标的物市场价格向买方所期望的方向变动的可能性越大

写作题

第二节：读写任务(满分25分)

请根据下面的任务和写作要求，写一篇150 词左右的英语短文，并把文章写在答题卡指定位置。

[写作内容]

你要参加一场英语辩论赛，主题为“是不是快乐没痛苦才是真正的幸福？”。在参赛之前，你查看相关的资料，并准备你的辩论发言。请认真阅读下面的短文，然后完成以下的任务。

1）概况短文内容要点，该部分的字数大约30：

2）就“是不是快乐没痛苦才是真正的幸福？”这个主题发表你的看法，至少包括以下内容要点，该部分的字数大约120：

l 以你自己为例，简述你对金钱、快乐的看法；

l 你如何看待快乐没痛苦才是真正的幸福的观点；

l 你的身边的同学如何对待快乐没痛苦才是真正的幸福的观点；

l 你对身边的同学的观点持什么看法？为什么？

[写作要求] 你可以使用实例和其他论述方法支持你的观点，也可以参照阅读材料的内容，但不要抄袭阅读材料中的句子。

[阅读材料]

The way people hold the belief that a fun-filled, pain-free lifestyle equals happiness actually reduces their chances of ever obtaining real happiness. If fun and pleasure are equal to happiness，then pain must be equal to unhappiness. But in fact，the opposite is true: more often than not things that lead to happiness contain some pain.

As a result，many people avoid the very attempts that are the source of true happiness．They fear the pain inevitably (不可避免地) brought by such things as marriage，raising children，professional achievement, religious commitment, self-improvement．

Ask a bachelor why he resists marriage even though he finds dating to be less and less satisfying. If he is honest，he will tell you that he is afraid of making a commitment，for commitment is in fact quite painful. The single life is filled with fun, adventure and excitement．Marriage has such moments, but they are not its most distinguishing features.

Couples，with infant children, are lucky to get a whole night’s sleep of a three-day vacation. We don’t know any parent who would choose the word fun to describe raising children. But couples that decide not to have children ever know the joys of watching a child grow up or playing with a grandchild.

Understanding and accepting that true happiness has nothing to do with fun is one of the most liberating realizations. It liberates time: now we can devote more hours to activities that can really increase our happiness. It liberates money: buying that new car or those fancy clothes to increase our happiness now seems pointless. And it liberates us from envy: we now understand that all those who always have so much fun actually may not be happy at all.