If you are like most people ,your intelligence (智力) changes with the seasons ,You are probably a lot sharper in the spring than you are at any other time of year . A famous scientist ,Ellsworth Huntington (1876—1947)，concluded (总结) from other men’s work and his own among people in different climates that climate and temperature have an effect (作用) on your mental abilities (智力).
He found that cool weather is much more favorable for creative (激活) thinking than summer heat .This does not mean that all people are less intelligent in the summer than they are during the rest of the year. It does mean, however , that the mental abilities of large numbers of people tend to be lowest in the summer .
Spring appears to be the best period of the year for thinking One reason may be that in the spring man’s mental abilities are affected(受影响)by the same factors (因素) that bring about great changes in nature .
Fall is the next-best season ,then winter .As for summer ,it seems to be a good time to take a long vacation from thinking .
Ellsworth Huntington decided that climate and temperature have ______

A．a great effect on everyone’s intelligence

B．some effect on most persons’ intelligence

C．some effect on a few persons’ intelligence

D．no effect on most persons’ intelligence

Why is spring the best season for thinking ? Because _______________.

A．all nature ,including man ,is growing then

B．it lasts longer than the other seasons

C．it is not too warm and not too cold

D．both B and C

The two best seasons for thinking seem to be _____________.

A．spring and fall	B．winter and summer
C．summer and spring	D．fall and winter

According to the passage, any vacation from thinking should be taken_____________ .

A．several times throughout the year	B．during the winter
C．during the summer	D．as seldom as possible

The main idea of this passage is that ____________.

A．most people’s intelligence changes with seasons

B．seasons are the reason of the changing intelligence

C．spring is the best season for thinking

D．summer is the best season for taking a long vacation