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 ...