求助

drake76

各位大虾，我有两道语法题不懂，希望能得到您的帮助。
In addition to having more protein than wheat does, the protein in rice is higher quality than that in wheat, with more of the amino acids essential to human diet.
1.        rice has protein of higher quality than that does
2.        rice has protein of higher quality than does
为什么答案是1，而非2。比较主语时，通常用助动词替代原来的谓语且用倒装的规则应该选2才对呀。

Acoording to a recent poll, owning and living in a freestanding house on its own land is still a goal of a majority of young adults, like that of earlier generations.
1.        like that of earlier generations.
2.        as it was of earlier generations.
为什么答案是2，而1又为什么不对呢？