【SAT】语法题求助!求分析.than平行结构.

题目

【SAT】语法题求助!求分析.than平行结构.
The primatologist has argued that sustained observation of a few animals provides better behavioral data than does intermittent observation of many animals.
　　(A) provides better behavioral data than does intermittent observation of many animals
　　(B) provides better behavioral data than many animals are observed intermittently
　　(C) providing better behavioral data than does intermittent observation of many animals
　　(D) do provide better behavioral data than intermittent observation of many animals do
　　(E) in contrast to intermittent observation of many animals,provides better behavioral data
应选A
than两边哪两个动词是平行的?还有为什么sustained后面可以跟provides,不是至少也是providing吗?

答案

宾语从句里只看前一部分：
sustained observation（主语） of a few animals（定语） provides（谓语） better behavioral data（宾语）.sustained是过去分词作定语,相当于形容词用法,修饰observation的.
比较状语从句的平行结构是：
intermittent observation（主语） of many animals（定语）(provides behavioral data).
放到than后面部分倒装,变成：does intermittent observation of many animals (provide behavioral data).括号里面相同部分省略了.