【求助】 07 prep 2 sc 25 关于比较 大家来看看啊

totalgloria

题目如下
There is a widespread belief in the United States and Western Europe
that young people have a smaller commitment to work and a career than their parents and grandparents and that the source of the change lies in the collapse of the "work ethic."


(A)
a smaller commitment to work and a career than their parents and grandparents
(B)
less of a commitment to work and a career than their parents and grandparents
(C)
a smaller commitment to work and a career than that of their parents and grandparents
(D)
less of a commitment to work and a career than their parents and grandparents had
(E)
a lessening of the commitment to work and a career that their parents and grandparents had

正确答案为D
这道题我主要在B和D两个选项间犹豫，两个选项的差异也仅仅在于最后的had.
在prep语法笔记里找到这道题的解释，里面说B选项缺少助动词had 会产生比较歧义。
比较歧义这个问题我理解，但是当时我没有选D的原因就是我觉得had这里应该是实意动词have的过去式，按理来说应当用did才对呀
所以我的问题就是
1) prep语法笔记对这个had的解释是不是有问题呢？这里had怎么会是助动词呢
2）在这种比较句型中，如果动词是实意，那么后面是不是只能用did，do等助动词来替代呢？
   举个例子：Mary eat an apple faster than I do. 可否说成 Mary eat an apple faster than I eat.
大家帮我解答下吧 谢谢啦~~

aeoluseros

嗯，had不是助动词，是实意动词.
FYI:
have/be/become/come这种是表示状态、特性的词，往往可以用原词，但是用助动词来代替也没错，而eat是描述动作的词，用do来替代更好.

rylstar01

个人觉得，在划线部分中出现了than，然后找划线部分的平行结构。
句中... young people have...than their parents and grandparents had...形成一个平行结构，即现在的年轻人的工作认同感与过去的他们的父辈和祖辈的工作认同感进行比较。如果没有had的话，则是现在的年轻人工作认同感与他们的父辈和祖辈比。这就显得不符合逻辑。有纰漏的地方还请楼主见谅：）

totalgloria

恩~ 谢谢版主来解答 嘿嘿 很清楚~~ 明白啦！