3. Computers are becoming faster, more powerful, and more reliable, and so too are modems, they are the devices to allow two or more computers to share information over regular telephone lines.
(A) so too are modems, they are the devices to allow
(B) so too are modems, the devices that allow
(C) so too modems, the devices allowing
(D) also modems, they are the devices that allow
(E) also modems, which are the devices to allow
答案是B,请问E少are以外，其他还有哪里有问题吗？
16. Migraine, the most debilitating common form of headache, afflicts perhaps 18 million Americans, who collectively lose 64 million workdays a year, and they cost the nation $50 billion in medical expenses and lost work time.
(A) year, and they cost the nation $50 billion in medical expenses and lost
(B) year and thus cost the nation $50 billion in medical expenses and lost
(C) year, so as to cost the nation $50 billion in medical expenses and lost
(D) year that costs the nation $50 billion in lost medical expenses and
(E) year, which thus cost the nation $50 billion in lost medical expenses and 答案是B，请问C为什么不对？
谢谢！ | 
