There is a widespread believe in the US and the 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... 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 这道题选D,有几个地方不明白想请教。。第一个答案D中的平行结构是young people have.... than their parenets and grandparents had,后面不是应该是...than their grandparents did,这样更符合平行结构么??还有就是为什么career前有个贯词a,大牛们可以帮忙解释这句话的结构么?