一个没讨论过的语法现象 TT GWD-7-18 vs TT GWD-7-1

关于2个so...that,第2个so 后的系动词要否省略问题，gwd的两道题似乎有点矛盾，请牛人指教，谢谢！！！

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.

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 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

有人说C错在so reflective前面缺系动词is,请教为什么 TT GWD-7-1的正确答案E却省略了系动词呢？

望高人不吝赐教，谢谢！

1. and her lobbying for wage and hour reform was persistent,
               
2. and lobbying for wage and hour reform was persistent, so that
               
3. her lobbying for wage and hour reform persistent, that
               
4. lobbying for wage and hour reform was so persistent,
5. so persistent her lobbying for wage and hour reform, that

Again, thank you for your attention

Still, it's hard for me to fully agree with u. 

So dogged were
                Frances Perkins’ investigations
            

so persistent
                        (was) her lobbying for wage and hour reform

The scenario is the same as what you mentioned but the result is different.

So dogged were Frances Perkins’ investigations of the garment industry, and
            so persistent was her lobbying for wage and hour reform, that Alfred E. Smith and Franklin D. Roosevelt recruited Perkins to work within the government, rather than as a social worker.

the phase 'so persistent her lobbying wage and hour reform' is used as a parenthesis to modify 'the garment industry'.

open to talk