名词和句子进行比较也可以吗？

GWD 21-1 >>

According to analysts, 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 with speeds much higher than is currently possible.>>

A. with speeds much higher than is>>

B. with speeds that are much higher than are>>

C. at much higher speeds as are>>

D. at much higher speeds than that  (E)

E. at speeds much higher than are

名词和句子进行比较也可以吗？

at speeds （which would be ）much higher than （speeds/those）are

括号内省略

为什么可以这么省呀？

凡是比较就能这么省？

是不是and平行就不能这样省呀？