题目内容：

    Even though vaccination (接种疫苗) is a powerful defense against disease, some voices are against it. In a recent letter, the American Medical Association (AMA) urged big social media including Amazon, Facebook and Google to take action to defend medical science on their platforms.

It said that vaccine -preventable diseases that do harm to the public health like measles (麻疹) are on the rise. Measles cases worldwide jumped more than 30% in 2017 compared to 2016, with the largest increases seen among nations in the Americas, Europe and the Eastern Mediterranean. Vaccine-preventable diseases are increasing largely because many people are unwilling to get vaccinated. And some of these people even encourage others to refuse vaccination. So this year, the World Health Organization (WHO) declared the anti-vaccination movement a top 10-health threat.

“Vaccination is one of the most cost-effective ways of avoiding disease—it currently prevents 2-3 million deaths a year, and a further 1.5 million could be avoided if global coverage of vaccinations improved,” WHO said.

A research article published in 1998 in a medical journal suggested a link between a vaccine and the development of autism (孤独症) in young children. Although the research has been suspected and many other studies have proved that vaccinations do not cause autism, the article is still impressing people strongly today. Another reason for the growth in the anti-vaccination movement is widespread misinformation on social media, which can turn people against vaccination.” If a concerned parent consistently sees information in their Newsfeed that casts doubt on the safety of vaccines, it could cause them to disregard the advice of their children’s physicians and public health experts and refuse to follow the recommended vaccination schedule. So access to true information about vaccine safety is badly needed.

1.What does the AMA require social media to do on their platforms?

A.Stop vaccine misinformation.

B.Unite to develop new vaccines.

C.Give up the anti- vaccination movement.

D.Introduce Vaccine-preventable diseases.

2.Why does the author mention the measles cases?

A.To declare measles can be prevented,

B.To show the result of anti-vaccination.

C.To prove some countries refuse vaccination.

D.To explain the reason for avoiding vaccination.

3.Which of the following play an important role in the anti- vaccination movement?

A.The costs of vaccination. B.The social media platforms.

C.The concerns of vaccine safety. D.The articles about autism.

4.Where is this text most likely from?

A.A novel. B.A brochure.

C.A diary. D.A magazine.