GWD一道语法题，请教~~

ambertun

GWD3-Q10:

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

我选B是根据前半部分，但是不知道were it to do so是什么用法，意思是不是，如果冰融化的话。。。

但是were 和it..

请大家指教，谢谢啦

songlovegt

虚拟语气。
if it were to do so, 虚拟语气里用were 不管主语是单数还是复数

ambertun

谢谢：）

山竹

为什么这里不用if it were to do so呢？为什么倒装呢？