a big headache 令人头痛的事情

a fraction of 一部分

a matter of concern 焦点

a series of 一系列，一连串

above all 首先，尤其是

absent from 不在，缺席

abundant in 富于

account for 解释

accuse sb of sth 控告

add to/add up to 增加

after all 毕竟，究竟

agree with 同意

ahead of time/schedule 提前

ahead of 在

alien to 与

all at once 突然，同时

all but 几乎；除了

all of a sudden 突然

all over again 再一次，重新

all over 遍及

all right 令人满意的；可以

all the same 仍然，照样的

all the time 一直，始终

angry with sb at/about sth 生气，愤怒

anxious about/for 忧虑，担心

anything but 根本不

apart from 除

appeal to 吸引，申诉，请求

applicable to 适用于

apply to 适用

appropriate for/to 适当，合适

approximate to 近似，接近

apt at 聪明，善于

apt to 易于

around the clock 夜以继日

as a matter of fact 实际上

as a result(of) 因此，由于

as a rule 通常，照例

as far as ... be concerned 就...而言

as far as 远至，到...程度

as follows 如下

as for 至于，关于

as good as 和

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