经典总结英语四级作文八种常用句型 一)原因 1.A number of factors are accountable for this situation. A number of factors might contribute to (lead to )(account for ) the phenomenon(problem). 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 .largely results from the fact that. 6. We may blame .,but the real causes are. 7. Part of the explanations for it i