In the United States, 30% of the adult population has a “weight problem”. To many people, the cause is obvious（明显的）: they eat too much. But scientific evidence does little to support this idea. Going back to the America of the 1910s, we find that people were thinner than today, yet they ate more food. In those days people worked harder physically（体力上）, walked more, used machines much less and didn’t watch television.
Several modern studies, moreover, have shown that fatter people do not eat more on the average than thinner people. In fact, some investigations（调查）, such as the 1979 study of 3,545 London office workers, report that, on balance, fat people eat less than slimmer people.
Studies show that slim people are more active than fat people. A study by a research group at Stanford University School of Medicine found the following interesting facts:
The more the men ran, the more body fat they lost
The more they ran, the greater amount of food they ate.
Thus, those who ran the most ate the most, yet lost the greatest amount of body fat.
The physical problem that many adult Americans have is that ______.

A．they are too slim	B．they work too hard
C．they are too fat	D．they lose too much body fat

According to the article, given 500 adult Americans, ______ people will have a “weight problem”.

A．30

B．50

C．100

D．150

Is there any scientific evidence to support that eating too much is the cause of a “weight problem”?

A．Yes, there is plenty of evidence.

B．Of course, there is some evidence to show this is true.

C．There is hardly any scientific evidence to support this.

D．We don’t know because the information is not given.

In comparison with the adult American population today, the Americans of the 1910s ______.

A．ate more food and had more physical activities

B．ate less food but had more activities

C．ate less food and had less physical exercise

D．had more weight problems

Modern scientific researches have reported to us that ______.

A．fat people eat less food and are less active

B．fat people eat more food than slim people and are more active

C．fat people eat more food than slim people but are less active

D．thin people run less, but have greater increase in food intake