题目

基因型为AaBb(两对基因分别位于非同源染色体上)的个体，在一次排卵时发现该卵细胞的基因型为Ab，则在形成该卵细胞时，随之产生的极体的基因型为（    ）Ａ.Ab.ab.ab；Ｂ.Ab.aB.aB； Ｃ.Ab.aB.ab；Ｄ.ab.AB.Ab。 答案：B  该题要注意减数第一次分裂是同源染色体分开，非同源染色体自由组合；而第二次分裂是有关着丝点断裂Good morning, boys and girls. Today I’ll give you a talk about going online.We know that there are too many Net bars(网吧) around us. The Internet makes our lives interesting. Many of us like going online very much because we can learn how to use the computer. We can learn English and read some newspapers and magazines to know more information around us. It can make us clever in playing computer games. Also when we send e-mails to our friends, they can get them right away. It can help us keep in touch with people from all over the world.But some students spend too much time in playing computer games and some stay in the Net bars all day and all night. It takes them too much time to chat online so they do worse in their lessons and they don’t study well any more. I think we mustn’t get online when it is time for us to study. We can do it in summer or winter holidays. I think we should get online with our teachers or parents.At the same time, if we have lots of free time, we can do some activities after school. We usually have activities from 4:50 to 5:50 in the afternoon. We can play basketball or football. We also have some interest groups in school, such as drawing, singing and dancing. We can go to the English corner on Monday afternoon. I hope we can spend more time on our subjects or on such activities that we can learn a lot from and less time on the Internet.That’s all! Thank you.Title(标题):A1.about going online Advantages(优点) ●Make our lives2.●Learn how to use the computer and can get more3..●Send e-mails to our friends anytime and they can get them right4..●Help us keep in5.with people from all over the world. Disadvantages(缺点) ●It6.too much time to play computer games.●Some students spend too much time7.online, so they do8.in their lessons. Advice Do it in summer or winter holidays; do some9.activities and have some10.groups in school.  1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 【解析】试题分析：这是一篇演讲稿，通过对学生们网络利用情况的分析，提出了上网的优点和不足，最后提到几点建议：参加课外活动、参加兴趣小组，例如画画,唱歌和跳舞。还可以去英语角，总之，正确利用网络是最好的。 1. 2. 3. 4. 5. 6. ...