Did you get a flu shot this year? For the first time, the Centers for Disease Control and Prevention in the US is recommending that all children aged from 6 months to 18 years receive the flu vaccine.
Vaccines battle diseases caused by bacteria and viruses.A weakened form of the germ (微生物)is introduced into the body.The body makes special substances called antibodies to fight the germs.If the actual germs were to attack, the antibodies would fight it.
Because there are many kinds of flu viruses, scientists must create a new vaccine formula(方程式) each year.Researchers must make a prediction.
It is like forecasting the weather.Sometimes they are right on, and sometimes they are off.But even when the vaccine does not closely match circulating flu types, it can make the illness less serious.
"The flu vaccine is not as effective as the polio(小兒麻痹癥)vaccine or the measles vaccine," says Dr William Schaffner of Vanderbilt University School of Medicine."It's not a great vaccine, but it is quite a good vaccine."
But a flu vaccine doesn't work for everyone.There are certain people who should be careful about taking it.
Because the vaccine is produced in eggs, those who are allergic(過(guò)敏的)to eggs should not take it.If you have a fever, you should wait until you recover.
Some people are afraid that they might get the flu from the flu shot.Scientists say that it is not possible, because the viruses in the flu shot are inactivated.But some minor side effects such as low-grade fever and body ache could occur.If they do, they begin soon after the shot and usually last only one to two days.
Did you know?
Smallpox was the first disease people tried to prevent by putting a virus into a healthy person.In 1796, English scientist Edward Jenner placed some infected material under a boy's skin.
1.By saying "It's not a great vaccine, but it is quite a good vaccine", the author means the flu vaccine .
A.is not as effective as the polio and measles vaccines
B.is not effective, compared with the polio and measles vaccines
C.does help to make illness less serious
D.is quite good because it works for everyone
2.We can infer from the passage that .
A.those who are allergic to eggs should not take flu vaccine
B.a(chǎn)ll the flu vaccines are not effective for everyone
C.you should go to a doctor if you have a fever or body ache after taking the flu vaccine
D.it is possible that some people might get the flu from the flu shot
3.It is not advisable for everyone to take flu vaccine because .
A.there are many kinds of virus
B.the flu vaccine is not as effective as the polio and measles vaccines
C.someone may be allergic to it
D.it has some minor side-effects
4.What topic will be discussed in the following paragraph?
A.What kind of people should be careful about taking smallpox vaccine.
B.The side-effects of smallpox vaccine.
C.The origin of the flu vaccine.
D.How the smallpox vaccine worked on the boy.
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You Are What You Eat
Genetic engineering is the scientific change of the genetic material in a living organism. It allows scientists to identify specific genes, to remove them from an organism's chromosomes (染色體), improve them, analyze them, and possibly clone them, and to then reinsert the changed gene into the original organism, or a completely different organism.Unlike traditional breeding, where a desired quality would be bred within the same species, genetic engineering can insert desired ones into organisms of different species. Wow…Did you catch that?
Genetic engineering creates many positive contributions to agriculture. For example, by genetically engineered(GE)foods, anti-cancer agents, minerals and vitamins can be increased. Improved taste, shelf life, and better transport are all possible. Also, GE plants can increase pest and bacterial resistance, therefore, making the food safe for consumers.
But some argue that the possible negative effects outweigh the positives, and critics are starting to voice their concerns. Unlike Europe, in the United States labeling is not required on genetically engineered foods or on foods that contain genetically engineered products. Most Americans do not realize that they are, in fact, eating GE foods.
The public is also concerned about the unknown health risks. With limited understanding of genes, scientists cannot predict possible effects. Because most genes introduced into GE plants come from sources not introduced into the human body, it is impossible to know if they will cause reactions. Moreover, due to the lack of labeling if allergies develop, it will be extremely difficult to find the origin of them.
There is also a major moral question in many minds. For many, the conflict is not if it is safe or not, but it disturbs them because it is unnatural and unnecessary. We are currently producing one and a half times the amount of food needed to feed the world, yet one in seven people are starving. GE food is unnecessary, and fails to address the root of hunger. Many believe that the only people who will benefit are the corporations that produce it.
Scientists cannot foresee the possible effects of GE foods, but we eat them every day without even knowing it. We already have enough food, so why create more that could be potentially harmful to us, to the Earth and to all wildlife? I think that the benefits are amazing, but until we know for sure how these foods will affect us, they are not worth the risk.
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C. we're now producing more food than before
D. customers will benefit from GE food
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