一)原因
1.A number of factors are accountable for this situation.
A number of factors might contribute to the phenomenon.
2. The answer to this problem involves many factors.
3. The phenomenon mainly stems from the fact that...
4. The factors that contribute to this situation include...
5. The change in ely results from the fact that...
6. We may blame ...,but the real causes are...
7. Part of the explanations for it is that ...
One of the most common factors is that ...
Another contributing factor is ...
Perhaps the primary factor is that
But the fundamental cause is that
二)比較
advantage far outweigh the disadvantages.
advantages of A are much greater than those of B.
3.A may be preferable to B, but A suffers from the disadvantages that...
is reasonable to maintain that it would be foolish to claim that...
all the disadvantages, it has its compensating advantages.
anything else, it has its faults.
7.A and B has several points in common.
