Read the passage.
Nearsightedness and Farsightedness
Nearsighted people experience blurred vision while looking at distant objects, such as street signs viewed from inside a car. Conversely, farsighted people experience blurred vision while looking at nearby objects, such as words on a page. The causes of these two conditions differ as well. Nearsightedness, or myopia, occurs either when a person's eye is too long from back to front or when the cornea (the clear layer at the front of the eye) is too curved. On the other hand, farsightedness, or hyperopia, results when the eye is too short or when the cornea is not curved enough. Fortunately, corrective lenses can restore normal vision in both cases. As you might expect, these lenses are of opposing types: nearsightedness is improved with a lens that is thinner in the middle and thicker at the edges, while farsightedness is compensated for with a lens that is thicker in the middle and thinner at the edges.
What is the main idea of the passage?

1.In nearsightedness, the eye may be too long from front to back, while in farsightedness, the opposite may be true.
2.Nearsightedness and farsightedness produce contrasting vision problems, have opposite causes, and require different types of lenses.

Read this excerpt from "herd about the flu." the flu shot prevent huge numbers of infections. even when it doesn't fully prevent infection in every person, the shot makes any flu infection less serious. on a global scale, the vaccine can reduce the number of infections only if most people in the community take it. that's because vaccines need to reach enough people to achieve a "herd immunity," the level of immunity needed to prevent the virus from spreading. if too few people get the vaccine, the people who receive it may not be well protected against infection. so the next time you are at the drugstore, and you see no flu shots available, think about the reasons behind it. drug makers are scared to make too many flu shots because they could lose too much money. they then make fewer flu shots and the effect of the flu shots becomes weaker because not enough people take it. people become more reluctant to take the flu shot since they don't think it will fully work. the demand goes down further and the flu companies make even fewer shots the next year. this could continue until the community changes its mind and we all get the flu shot. "that is a community responsibility," says the president of merck, one of the two remaining flu vaccine manufacturers. which argument best supports the passage's claim that more people should get the flu vaccine to stop the virus from spreading? 1.if too few people get the vaccine, the people who receive it may not be well protected against infection 2. so the next time you are at the drugstore, and you see no flu shots available, think about the reasons behind it. 3.people become more reluctant to take the flu shot since they don’t think it will fully work. 4.drug makers are scared to make too many flu shots because they could lose too much money.