[求助]GWD-19-40

best_tu

奇怪GWD19怎么都没人问的呢??

40.Agricultural societies cannot exist without staple crops.  Several food plants, such as kola and okra, are known to have been domesticated in western Africa, but they are all supplemental, not staple, foods.  All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams.  Therefore, discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.

Which of the following is an assumption on which the argument depends?

People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.

There are no plants native to western Africa that, if domesticated, could serve as staple food crops.

Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa.

Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are.

Kola and okra were domesticated in western Africa before rice and yams were introduced there.

答案选A,我选B,到底A是怎么推出来的呢??

求教,谢谢

best_tu

up

best_tu

没人回答吗??

wycg

以下是引用best_tu在2006-2-13 18:41:00的发言：

奇怪GWD19怎么都没人问的呢??

40.Agricultural societies cannot exist without staple crops.  Several food plants, such as kola and okra, are known to have been domesticated in western Africa, but they are all supplemental, not staple, foods.  All the recorded staple crops grown in western Africa were introduced from elsewhere, beginning, at some unknown date, with rice and yams.  Therefore, discovering when rice and yams were introduced into western Africa would establish the earliest date at which agricultural societies could have arisen there.

Which of the following is an assumption on which the argument depends?

1. People in western Africa did not develop staple crops that they stopped cultivating once rice and yams were introduced.


2. There are no plants native to western Africa that, if domesticated, could serve as staple food crops.


3. Rice and yams were grown as staple crops by the earliest agricultural societies outside of western Africa.


4. Kola and okra are better suited to growing conditions in western Africa than domesticated rice and yams are.


5. Kola and okra were domesticated in western Africa before rice and yams were introduced there.

答案选A,我选B,到底A是怎么推出来的呢??

求教,谢谢

B没有时间上的比较.

best_tu

谢谢WYCQ!!

那么忙还来回答我的问题!

感动!!

cournot

A说在大米和洋芋引进之前，西非人没有种植过其它的staple crops ，所以rice and yam是最早的staple crops =>rice and yams were introduced 的时间就是the earliest date at which agricultural societies could have arisen there

B只说西非自己没有staple crops ，但是可能会有从其它地方引进的staple crops 早于rice and yam=>农业社会最早的时间就不是大米和洋芋被引进的时间了。