题目内容：

    Summer is here, and with it comes a chance you'll get too much sun. While there's no cure for sunburn, a small but fascinating new study suggests taking large amounts of vitamin D after exposure may prevent the associated redness and inflammation (发炎).

In the paper, researchers exposed 20 volunteers to a light resembling solar radiation to induce a sunburn on a small piece of skin. They then gave the ''burn victims'' large amounts of vitamin D, and followed up with participants one, two and three days (and a week) later to measure skin redness and thickness. The researchers found that vitamin D decreased inflammation and redness, compared with taking a placebo (安慰剂). And this effect increased in proportion to how much was consumed. Vitamin D also appears to increase the activity of a gene called arginase-1, which is involved in tissue repair and healing. Taking 50, 000 international units (IU) of vitamin D--125 times the recommended daily allowance-led to a significant reduction in redness and inflammation, compared with the placebo. Those who took 100,000 IU had even less redness and pain; and those who took 200, 000 IU had the greatest reduction in inflammation.

This is the first study to show vitamin D can reduce inflammation, and suggests that it  ''could potentially help prevent sunburn, '' says senior author Kurt Lu, a physician scientist and assistant professor at Case Western Reserve University.

It used to be thought vitamin D was primarily involved in building healthy bones and muscles, but recent research has found it has many more roles, including influencing inflammation, such as the kind associated with sunburns.

So, if you get burned, should you take a lot of vitamin D? The study authors don't recommend it. ''I think that's probably not a good idea and not well established by this study, '' says Barbara Gilchrest, a physician scientist at Massachusetts General Hospital. Such large amounts, if taken repeatedly, have the potential to cause vitamin D toxicity (毒性).

1.What does this passage mainly talk about?

A.An unusual method for relieving sunburn.

B.Tips for how to travel safely in summer.

C.A suggestion on taking vitamin D properly.

D.Advice on how to take medicine effectively.

2.How do the researchers confirm the healing effect of taking vitamin D?

A.By observing the inflammation of skin every day.

B.By measuring the thickness of skin after a week.

C.By increasing the daily volume of vitamin

D.By comparing the effect with that of placebo.

3.Figures are used in paragraph 2 in order to ______.

A.recommend the daily intake

B.argue against the benefits of more Vitamin D

C.show the more Vitamin D, the greater benefits

D.stress the potential danger of too much Vitamin D

4.What can be inferred about the function of vitamin D?

A.Repeatedly taking large amounts of Vitamin D is beneficial.

B.Vitamin D may bring more advantages to us than what has been found out.

C.Don't take vitamin D unless your doctor approves you to do it.

D.Vitamin D is more useful for curing sunburn than building healthy bones.