题目内容：

    Getting active in midlife could be as good for you as starting young when it comes to reducing the risk of an early death, researchers have suggested. But experts say the study also shows that the benefits fade once exercise declines.

“If you maintain an active lifestyle or participate in some sort of exercise from youth to middle age, you can reduce your risk for dying,” said Dr. Pedro Saint-Maurice, the lead author of the research. “If you are not active and you get to your 40s - 50s and you decide to become active, you can still enjoy a lot of those benefits.”

The study was based on data from more than 300,000 Americans aged 50 - 71 who undertook a questionnaire(问卷) in the late-1990s. They were asked to recall the extent of their moderate to vigorous leisure exercise at different stages of their life. Researchers then used national records to track who died in the years up to the end of 2016. After taking into account factors including age, sex, smoking and diet, the team found that those who were exercising into middle age had a lower risk of death than those who had never carried out any leisure exercise. However, when the team looked at different patterns in the way people were active over their life, it found a surprise.

Men and women who started exercising at the age of 40 - 50 reduced their risk of death from any cause by about 35%. The benefit was similar to that seen for people who reached and maintained similar activity from their teens or 20s onwards.

However, the study found that the protective effect of exercise did not last forever. People whose levels of leisure exercise decreased by middle age had no difference in the risk of an early death to those who had always been couch potatoes. “If you have been active and you slowly decrease your exercise participation as you age, you lose a lot of the benefits that we know are associated with exercise,” Saint - Maurice said.

But the study has limitations, including that it is based on individuals recalling how active they were many years before. What’s more, the research looked only at death records, not other aspects of health such as levels of sickness and disease. Nonetheless, he said, the message was positive. “This adds to the growing body of evidence about the importance of physical activity and exercise across he life course, and indicates that it is never too late to start.”

1.Which of the following is TRUE about the study?

A.The study took about two decades to complete.

B.The study involved around 30,000 elderly Americans.

C.Questionnaires and interviews were the sources of data.

D.The participants in the study took regular physical exercise.

2.According to the passage, what does “a surprise” (Para.3) refer to?

A.The earlier you exercise, the greater your health benefits will be.

B.Participating in exercise from youth to middle age benefits one’s health greatly.

C.The benefit of getting active in midlife is similar to that of starting young.

D.The benefits of exercising in midlife will decline once you stop exercising.

3.It can be inferred from the passage that _________.

A.an active lifestyle will not necessarily bring positive health benefits.

B.participants’ memories may affect the reliability of the study result

C.people exercising from their teens can maintain health forever

D.women benefit more from vigorous exercise than men do

4.Which of the following might be the best title of the passage?

A.Exercise has its limitations, studies show

B.Getting active when young, experts suggest

C.Health benefits fade with age, doctors warn

D.Never too old to start, researchers say