[简答题]从电视上看到美国正流行甲型H1N1流感(A/H1N1 flu)，部分学校停课，你为正在美国上学的笔友Mike的健康与安全担心。请你根据要点提示立即给他写一封e—mail，询问他的情况，并给他提出防护建议。
要点：
一、询问
1．他的健康状况；
2．他们学校有无甲型H1N1流感病例(A/H1N1 flu cases)；
3．他们是否还上学。
二、建议
1．尽量待在家里，少去人多的地方；
2．勤洗手，讲卫生；
3．多开窗，保持空气新鲜；
4．多吃水果蔬菜。
注意：
1．词数在80词左右；
2．开头和结尾已给出，不计人总词数。
Dear Mike,
From TV I know many A/H1N1 flu cases are reported recently in the United States, and many schools are closed as a result. I’m so worried about you.
So far the disease is not so deadly as it seems to be. Do be at ease! Take care and you’ll be OK.
Yours truly,
Li Hua

[单项选择]An epidemic of swine flu (猪流感) has recently developed in Mexico and the United States, says the CDC. Swine flu has killed many people, and the outbreak has features that suggest it could become a global pandemic (瘟疫). A pandemic is an epidemic that spreads around the whole world. Pandemics also often cause more severe disease than epidemics.
Flu is a disease caused by the influenza virus. Humans, pigs, birds and other animals all can be infected by influenza viruses. Typically, influenza viruses can infect only one species, so the influenza viruses of humans are different from those of pigs and birds. However, sometimes a virus can infect more than one species. For examples, pigs sometimes can be infected not only with pig influenza viruses, but also with human and bird influenza viruses. Then these viruses can come up to one another secretly and swap (交换) genes, creating new viruses that have a mix of genes -- from human, pig, and bird viruses. That is what has happened with th
A. kills those who are infected
B. always follows an epidemic
C. is the same as an epidemic
D. is widespread and serious

[单项选择]Most viruses that cause swine flu or bird flu are very hard to pass from one human to another: they don’t cause epidemics. Sometimes, however, further changes in genes create a virus that can spread rapidly among humans, and can produce a more severe illness. One reason this illness is more severe is that the virus is so new. The regular flu that comes each year is caused by a regular human influenza virus that often has similarities to the viruses that have caused the nu in years past, so people have some degree of immunity to the latest virus. The unusual swine flu or bird flu viruses that develop the ability for person-to-person spread are so different that people have little or no immunity to them.
What is the main reason that the swine flu is very dangerous to humans
A. That it is fatal and has killed many. B That it has spread to many countries.
C. That people know nothing about it. D. That people have no immunity to it.

[单项选择]流感杆菌
A. 能在高盐6.5%的NaCl生长的细菌
B. 生长需要V因子+X因子的细菌
C. 可进行冷增菌的细菌
D. 在pH值6.0～10.0均能生长的细菌
E. 菌落形态呈黏液状，互相融合，接种已拉成丝的细菌

[单项选择]流感病毒
A. 一般不引起细胞病变效应
B. 细胞内形成多型核巨细胞
C. 易发生基因重排
D. 主要通过血液传播
E. 细胞核内形成嗜酸性包涵体

[单项选择] 流感通过
A. 空气传播
B. 接触传播
C. 血液传播
D. 蚊虫叮咬传播
E. 消化道传播

[多项选择]What are the symptoms of swine flu
A. Chills, fever, and sore throat
B. Muscle pains and headache.
C. Shedding tears, sneezing and toothache.
D. Coughing, weakness and discomfort.

[单项选择]流感病毒发生变异，引起流感流行
A. 环境因素不变，病因比重增加
B. 宿主因素发生变化，宿主比重增加
C. 病因、宿主、环境三要素保持动态平衡
D. 环境因素发生变化，导致病因比重增加
E. 环境因素发生变化，导致宿主比重增加

[单项选择]由于流感病毒的变异引起流感流行属于
A. 在流行病学三角模型中，环境因素不变，病因比重增加
B. 宿主因素发生变化，宿主比重增加
C. 病因、宿主、环境三要素保持动态平衡
D. 环境因素发生变化，导致病因比重增加
E. 环境因素发生变化，导致宿主比重增加