第1个回答 2010-12-25
The question is so difficult that only a few people can work it out.
第2个回答 2010-12-25
This problem is so difficult that few people worked it out.
第3个回答 2010-12-25
It's such a difficult problem that few people can work it out
第4个回答 2010-12-25
The question is so difficult that few people can work it out.
第5个回答 2010-12-26
The question is so difficult that few people can work it out.