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DD答案其他我没啥看法（我选的B），就想问问have作为实义动词在做平行补充的时候可以用had来替代did么？
Scientists believe that unlike the males of most species of moth, the male whistling moths of Nambung, Australia, call female moths to them by the use of acoustical signals, but not olfactory ones, and they attract their mates during the day, rather than at night. A.by the use of acoustical signals, but not olfactory ones, and they attract
B.by the use of acoustical signals instead of using olfactory ones, and attracting
C.by using acoustical signals, not using olfactory ones, and by attracting
D.using acoustical signals, rather than olfactory ones, and attract
E.using acoustical signals, but not olfactory ones, and attracting正确答案D， 想问问这里using这里是否讲求逗号的使用，亦或说可不可以用逗号隔开？
要考了，谢谢各位XDJM
-- by 会员 fannyboy (2012/12/11 11:25:19)