GWD05-18请教，还没有讨论过

skyguard2000 · 发表于 2005-2-18 10:22:00

Q18:

Antarctica receives more solar radiation than does any other place on Earth, yet the temperatures are so cold and the ice cap is reflective, so that little polar ice melts during the summer; otherwise, the water levels of the oceans would rise 250 feet and engulf most of the world’s great cities.

A.is reflective, so that little polar ice melts during the summer; otherwise,

B.is so reflective that little of the polar ice melts during the summer; were it to do so,

C.so reflective that little polar ice melts during the summer, or else

D.reflective, so that little of the polar ice melts during the summer, or

E.reflects so that little of the polar ice melts during the summer; if it did

为什么C不行，我能不能认为is被省略了？答案是B，B选项中的were it to do so是什么用法？

[此贴子已经被作者于2005-2-18 10:29:12编辑过]