一)原因
1.A number of factor are accountable for thi ituation.
A number of factor might contribute to (lead to )(account for ) the phenomenon(problem)。
2. The anwer to thi problem involve many factor.
3. The phenomenon mainly tem from the fact that
4. The factor that contribute to thi ituation include
5. The change in largely reult from the fact that
6. We may blame ，but the real caue are
7. Part of the explanation for it i that
One of the mot common factor (caue ) i that
Another contributing factor (caue ) i
Perhap the primary factor i that
But the fundamental caue i that
二)比较
1.The advantage far outweigh the diadvantage.
2.The advantage of A are much greater than thoe of B.
3.A may be preferable to B， but A uffer from the diadvantage that
4.It i reaonable to maintain that but it would be foolih to claim that
5.For all the diadvantage， it ha it compenating advantage.
6.Like anything ele， it ha it fault.
7.A and B ha everal point in common.
8.A bear ome reemblance to B.