问一道过去没有定论的题 谢谢

GWD21-1

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.

1. with speeds much higher than is
2. with speeds that are much higher than are
3. at much higher speeds as are
4. at much higher speeds than that
5. at speeds much higher than are

这题答案是E.可我就是不明白这个 are咋回事啊......以前的讨论贴都没有定论啊....个个都不肯定的...