Prehistoric men and women enjoyed a more varied diet than people do now, since they ate

species of plant and several hundreds thousands types of living things. But only a tiny percentage of these were ever domesticated. Modern shops have hastened a trend towards specialization which began in the earliest days of agriculture. The food of the rich countries has become cheaper relative to wages. It is speedily distributed in supermarkets. But the choice annually becomes less and less great. Even individual foods themselves become more standardized. We live in the world of carrot specially blunted in order to avoid making a hole in the bag, and the tomato grown to meet a demand for a standard weight of weighting tomatoes to a kilo. Siri von Reis asks: "Only the three major cereals (谷物类食物) and perhaps ten other widely cultivated species stand between famine and survival for the world's human population and a handful of drug plants has served Western civilization for several thousand years. A rather obvious question arises: Are we missing something？" After all, there are 800 000 species of plant on earth.

1、In prehistoric times people____.

A、ate much more than we do today

B、lived mainly on plant food

C、had a wide-ranging diet

D、were more fussy about what they ate

2、Most of us have come to expect____.

A、no variation in our diet

B、a reduction in food supplies

C、a specialist diet

D、food conforming to a set standard

3、The specialization of food was started by____.

A、the emergence of supermarkets

B、the rise of agriculture

C、the rich countries

D、the modern shops

4、According to the passage, people in the West today survive on____.

A、carrots and tomatoes

B、several thousand types of plants and cereals

C、a very small number of cultivated foods

D、special species planted one thousand years ago

5、The conclusion seems to be that we____.

A、could make use of more natural species

B、don't cultivate the right kind of food

C、produce more food than we need

D、cultivate too many different species