GWD19-40（逻辑）拜托了哦~~~

月下无泪

Q40
Agricultural societites 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 hav arisen there.

which of the following is an assumption on which the argument depends?
A. people in western africa did not develop staple crops that they stopped cultivating once rice and yams were introduced
为什么是这个选项啊，我的理解是它既然did not develop staple crops, 那么它stopped cultivating什么啊，好吧，估计我的理解有问题

谢谢回复了哦：）

大胖

A 取非。 因为rice and yams were introduced ，所以原来种的staple crops 就没有再种了。 说明还有更早的staple crops  削弱观点。

月下无泪

这样理解啊~~~~

谢谢哦~~~

那做题的时候这样理解岂不是很浪费时间？？