[求助]蓝皮Section10

1.According to analyses,an alliance between three major personal computer companies and most of the nation's largest local telephone companies would enable customers to receive Internet data over regular telephone lines________currently possible.

D.at much higher speeds than that

E.at speeds much higher than are

为什么D错呢？than前无be动词与答案中的are对应啊？

2.When drive-ins were at the height of their popularity in the late 1950’s, some 4,000 existed in the United States, but today there are less than one-quarter that many.

C. There are fewer than one-quarter of that amount.
    

D. The number is less than one-quarter that amount.

不是通常优选less而非few么？D为什么错呢？还有请教一下there be在什么情况下适用啊？

3.1.Scientists have dated sharp-edged flakes of stone found in the fine-grained sediments of a dry riverbed in the Afar region of Ethiopia to between 2.52 and 2.60 million years ago, pushing back by more than 150,000 years the earliest date when it is known that humans made stone tools.

A. when it is known that humans made
    

B. at which it is known that humans had made
    

C. at which humans are known to have made
    

D.that humans are known to be making
    

E. of humans who were known to make

答案给的是E，发现好像有人说是A，我选了C，总之一片迷茫，望高人指点啊！

4. Almost like clones in their similarity to one another, the cheetah species’ homogeneity makes them especially vulnerable to disease.

A.      the cheetah species’ homogeneity makes them especially vulnerable to disease

C.     the homogeneity of the cheetah species makes it especially vulnerable to disease

D.     homogeneity makes members of the cheetah species especially vulnerable to disease

E.     members of the cheetah species are especially vulnerable to disease because of their homogeneity

这题我选C，但不知道哪儿做错了？此题考点是什么啊？

顶一下啊！