题干

基因工程又叫做基因拼接技术.该技术能够通过对生物的基因进行改造和重新组合,产生出人类所需要的基因产物.自20世纪70年代基因工程发展起来以后,人们开始采用高新技术生产各种基因产品.下表中列出了几种限制酶识别序列及其切割位点,图1和图2示基因工程部分操作过程:

限制酶

BamHⅠ

HindⅢ

EcoRⅠ

SmaⅠ

识别序列及切割位点

G↓GATCC CCTAG↑G

A↓AGCTT TTCGA↑A

G↓AATTC

CTTAA↑G

CCC↓GGG

GGG↑CCC

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    Today.an increasing number of people are always looking at their mobile phones with their heads down. These people are called the " Heads-down Tribe (低头族)". Are you a head-down tribe member? Heads-down tribe members now can be seen everywhere.

More and more traffic accidents are happening because more drivers use mobile phones when they are driving. In order to make drivers pay more attention to driving, some new traffic rules have been made. For example, people who use mobile phones while driving in Taiwan are fined(罚款). Car drivers and motorcyclists who break the traffic rule will be fined NT$ 3,000 and NT$1,000 respectively(分别地)

As we can see above, using mobile phones may cause accidents and even cost a lot of money. Also,more and more interesting and strange facts happen to the "Heads-down Tribe". Let's have a look at an interesting TV report. A man in America kept using his mobile phone on his way home. As a result, he knocked into a big lost bear. When he lifted his eyes from the phone, he was so afraid that he turned around and ran away quickly. Another fact is that we can often see people in the restaurant eating face to face but looking at their own mobile Phones. It's strange that they don't talk to the ones who sit opposite to them during the meal. Some of them even have fun communicating with others on the phone.

    Mobile phones are helpful and necessary tools for modern life. Are mobile phones good or bad? It depends on how people use them. Let's be "healthy" users and try to be the "Heads-up Tribe".