[求助][求助]GWD4-28

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.

1. is reflective, so that little polar ice melts during the summer; otherwise,
           
2. is so reflective that little of the polar ice melts during the summer; were it not to do so,
           
3. so reflective that little polar ice melts during the summer, or else
           
4. reflective, so that little of the polar ice melts during the summer, or
           
5. reflects so that little of the polar ice melts during the summer; if it did

（1） were it not to do so 还原了是  if it were not to do so，如果 it 是指代to do so，do so指代melt，那就是说冰不融化使得海面上升，意思不对了，但是如果do so不是这个意思，又是指的什么呢？

（2）另外，C选项错误是因为省略了is吗？并列句的be动词省略是不是不能用are代替is啊？

各位NN指教指教啊，十天后就要“升天”啦……

这道题目似乎有争议

我个人倾向选C

B 对吧?

yet the temperatures are so cold and the ice cap is so reflective .......

.were it not to do so,是虚拟语气倒装 the water levels of the oceans would rise 250 feet and engulf most of the world’s great cities.

http://forum.chasedream.com/dispbbs.asp?BoardID=23&ID=237478&replyID=2229029&skin=1

两题中的B差了一个not, 差了十万八千里