题目内容：

    Forget drinking countless glasses of water or getting your beauty sleep．The secret of looking young is simply to stay out of the sun．

A study of hundreds of women has revealed that those who avoided the sun’s rays looked up to 20 years younger than they actually are. However, other supposed rules for a youthful complexion, from drinking lots of water to sleeping well and exercising regularly, failed to hold back the hands of time.

Only keeping out of the sun, and wearing sunscreen when this wasn’t possible, made a difference, the American Academy of Dermatology’s annual conference will hear today.

The finding comes from a study of 231 women of all ages who were quizzed about their lives, including whether they were sun-loves. When researchers from Massachusetts General Hospital in the US guessed how old the women were, they found those who took care in the sun tended to have aged more slowly.

Four lucky women had so few wrinkles and age spots and such a glowing complexion，that they appeared to be twenty years younger than they really were．

Researcher Dr．Alexa Kimball said the popular belief that we drink lots of water to stay healthy is false and the body is “pretty good” at judging how much we need．Previous research by the British Nutrition Foundation reached a similar conclusion．

It isn’t clear why the women who slept well didn’t have younger-looking skin．But it may be that the question they were asked was too narrow and didn’t consider their long-term sleep patterns．

1.Which way can help women stay younger according to the study?

A. Having a good sleep． B. Drinking plenty of water．

C. Taking exercise regularly． D. Keeping out of the sun．

2.How did the researchers know the finding about women of all ages?

A. Through calls． B. Through games．

C. By quizzes． D. By interviewing face to face．

3.What’s the main purpose of the passage?

A. To introduce a good way to make women look younger．

B. To explain how scientists carried out the research．

C. To prove people’s previous ideas are true．

D. To persuade women to change their long-term sleep patterns．

4.This passage is most probably taken from______________．

A. a school textbook． B. a science fiction．

C. a reference book． D. a science paper．