The principal difficulty faced by the schools has been the tremendous increase in the number of pupils.
学校面临的主要困难是学生人数的大量增加。
2
These sources preserve different traditions on the number and the nature of the plagues, as well as the principal actors in the drama: God, Moses, Aaron.
这些资料保存了不同的传统关于瘟疫的数量和性质，以及戏剧中的主要角色：上帝，摩西，亚伦。
3
The condition appears to result from the cumulative effect of a number of factors, with atmospheric pollutants the principal culprits.