3-1-1. 基本原因 --- 分析某事物時, 用此句型說明其基本的或者多方面的原因.
[1]. why ... ? for one thing.. for another ...
[2]. the answer to this problem invovles many factors. for one thing... for another...... still another ...
[3]. a number of factors , both physical and psychological affect .... /both individual and social contribute to ....
3-1-2 另一原因 --------> 在分析了基本原因之後, 再補充一個次要的或者更重要時用!
[1]. another important factor is ....
[2]. ... is also responsible for the change/problem.
[3]. certainly , the ... is not the sole reason for ....