absence from 缺席，不在　
e.g. His long absence from work delayed his promotion.
       他长期不上班，耽误了提升。  

absence of 缺乏
e.g. 1、In the absence of my commanding officer, I acted on my own initiative.
　　      指挥官不在场，我主动见机行事。
　　 2、In the absence of their teacher the class was in a state of anarchy.
　　      教师不在，班上一片混乱。

access to …… 的入口，通路　
e.g. 1、The only access to the farmhouse is across the fields.
            要到那农舍去唯有穿过田地。
       2、She was forbidden access to the club.
            人家不允许她到那个俱乐部去。

acquaintance with 相识，了解　
e.g. 1、I have only a nodding acquaintance with Japanese.
　　      我对日语仅略知一二。
　　 2、The guide has some acquaintance with Italian.
　　      导游懂得一点意大利语。

action on sth 对……的作用　
e.g. evidences of glacial action on the rocks 岩石上的冰河留下的痕迹

addition to sth 增加
e.g. 1、She is a beautiful addition to the family.
　　      她是我们家漂亮的新成员。
　　 2、Can we finance the addition to our home?
　　      我们可以为你提供经费。

admission to /into 进入；入(场，学，会等)　
e.g. 1、How does one gain admission to the Buckingham Palace?
　　      怎样才能获准进入白金汉宫？
　　 2、Admission to British universities depends on examination results.
　　      英国大学入学以考试成绩为凭。

admission of sth 承认
e.g. 1、His admission of guilt surprised everyone.
　　      他供认犯罪使大家感到意外。
       2、The write of the letter is ipso facto an admission of guilt.
　　      写此信的本身就是一种认罪。

advance in 改进,进步
e.g. 1、an advance in genetic engineering
　　     遗传工程学方面的进展
　　 2、to advance in years
　　     年纪增长

advantage over 优于……的有利条件
e.g. Now we have won an advantage over the enemy.
　　 我们现在经赢得了对敌人的优势。