编辑分析：“Facing the conflict…” This sentence is somewhat unclear, especially upon the first reading. I have attempted to clarify the situation.
改正后：Facing a conflict between the need to take on extra responsibilities to alleviate a shortage of teachers at the school and preparing for the TOEFL, she chose to instruct students in courses of Mechanical CAD.
（6）原句： It is evident that burden of work effected her preparation for TOEFL, because she got GRE 2100 under less pressure from work.
编辑分析： “It is evident” I have rephrased for clarity and improved flow. “effected” affected.
改正后：That burden of increased work negatively affected her preparation for TOEFL, as demonstrated by her significantly better score on the GRE when she faced less pressure from work.
（7）原句：When she decided to leave us, although I, as director of this school, hate to let her go, I would like to renew my support for her today, as she sets her eyes on still grander horizons.
编辑分析： “I, as director…” I is unnecessary and confuses the sentence.
改正后：When she decided to leave us, though as director of this school I hate to see her go, I offered my full support. I would like to renew my support for her today, as she sets her eyes on still grander horizons.
（8）原句：I dearly hope that you will consider his application favorably.
编辑分析： “dearly hope” sincerely. “consider his application” her application. You have referred to the recommended teacher as ‘she’ and ‘miss’ throughout.
改正后：I sincerely hope that you will consider her application favorably and am confident you will be enlightened by her talents at your school.
总体评论：
千疮百孔的英文，语法错误、用词不当、句子结构不恰当，都可以分散阅读者的注意力，给阅读者造成误解，无法看懂你究竟要说什么。要知道评审委员要阅读上百份申请材料，你的错误可能使他（她）丧失对你的兴趣和信心。