Yeasts capable of leavening bread are widespread, and in the many centuries during which the ancient Egyptians made only unleavened bread, such yeasts must frequently have been mixed into bread doughs accidentally.The Egyptians, however, did not discover leavened bread until about 3000 B.C.That discovery roughly coincided with the introduction of a wheat variety that was preferable to previous varieties because its edible kernel could be removed from the husk without first toasting the grain.
Which of the following, if true, provides the strongest evidence that the two developments were causally related? A.Even after the ancient Egyptians discovered leavened bread and the techniques for reliably producing it were well known, unleavened bread continued to be widely consumed.
B. Only when the Egyptians stopped the practice of toasting grain were their stone-lined grain-toasting pits available for baking bread.
C. Heating a wheat kernel destroys its gluten面筋, a protein that must be present in order for yeast to leaven bread dough.
D. The new variety of wheat, which had a more delicate flavor because it was not toasted, was reserved for the consumption of high officials when it first began to be grown.
E. Because the husk of the new variety of wheat was more easily removed, flour made from it required less effort to produce.
作者: richardyam15 时间: 2010-9-15 14:47
题目问的two developments指的是1，yeasts must frequently have been mixed into bread doughs accidentally；2， introduction of a wheat variety that was preferable to previous varieties。而 introduction of a wheat variety that was preferable to previous varieties正好让古埃及人去除了toast（heating）这一步骤，也就保留了gluten，从而让leavened bread成为可能。作者: jessiecg 时间: 2010-9-15 14:55
不是很理解。。。。作者: richardyam15 时间: 2010-9-15 15:14
古埃及人本来弄那个wheat的时候要先toast以后再吃，而同时就正由于heat，让他们没法发现leaven面包的办法因为在heat的时候所需要的东西被heat去掉了。但是后来发现的不需要toast就可以吃的wheat让他们skip了heat，从而保留了leven面包所需要的protein，这就符合题目问的causally related，因为b事件的发生（现），意外的让a事件发生了作者: jessiecg 时间: 2010-9-15 15:22
恩 明白了 谢谢~
