题目内容：

    We’ve known that sitting for long periods of time every day has countless health consequences, like a higher risk of heart disease. But now a new study has found that sitting is also bad for your brain.

A study published last week, conducted by Dr. Prabha Siddarth at the University of California, showed that sedentary（久坐的）behavior is associated with reduced thickness of the medial temporal lobe（中颞叶）, a brain area that is critical to learning and memory.

The researchers asked a group of 35 healthy people, ages 45 to 70, about their activity levels and the average number of hours each day spent sitting and then scanned their brains. They found that the subjects who reported sitting for longer periods had the thinnest medial temporal lobes. It means that the more time you spend in a chair the worse it is for your brain health, resulting in possible damage to learning and memory.

What is also interesting is that this study did not find a significant association between the level of physical activity and thickness of this brain area, suggesting that exercise, even severe exercise, may not be enough to protect you from the harmful effects of sitting.

It then surprisingly turned out that you don’t even have to move much to enhance cognition（认知）; just standing will do the trick. For example, two groups of subjects were asked to complete a test while either sitting or standing. Participants are presented with conflicting stimuli（刺激）, like the word “green” in blue ink, and asked to name the color. Subjects thinking on their feet beat those who sat by a 3-milicond margin.

The cognitive effects of severe physical exercise are well known. But the possibility that standing more and sitting less improves brain health could lower the bar for everyone.

I know, this all runs counter to received ideas about deep thought, from our grade school teachers, who told us to sit down and focus, to Rodin’s famous “Thinker,” seated with chin on hand.

They were wrong. You can now all stand up.

1.What can we infer from Paragraphs 3 and 4?

A.Severe exercise can lessen the damage of sitting.

B.Severe exercise can greatly improve our brain health.

C.Sedentary behavior will possibly damage our brain.

D.Brain health has nothing to do with sedentary behavior.

2.What does the underlined word “margin” in Paragraph 5 mean?

A.blank. B.edge.

C.decrease. D.difference.

3.What is the received idea about deep thought?

A.Sitting more is good for our mental health.

B.Sitting is better when we think.

C.Exercise more can improve our cognition.

D.We should stand while thinking.

4.The passage mainly tells us ________.

A.people tend to sit while thinking

B.standing more can make our brain healthier

C.physical exercise can improve our brain health

D.sedentary behavior leads to countless health problems