碍事【ài shì】
be in the way; impede the progress of an affair; be a hindrance
[动短] 1、妨碍做事，造成不方便 2、严重，大有关系
我们应该限制参加这项工程的人数，因为人多反而碍事。
A limit should be put to the number of the people involved in the project, for too many people would become a hindrance.
只是擦破点儿皮，不碍事的。
It doesn't matter because It is just a minor bruise.
安【ān】
1. ease; settle down 2. install 3. quiet; calm; peaceful; tranquil; safe
[动] 1、使平静 2、安装，设置 [形] 3、平静，稳定
只有国家强盛了，人民才能安居乐业。
People can not lead a peaceful and prosperous life unless their country becomes strong.
如今，中国的大部分家庭都安上了电话。
Nowadays, most households in China have telephone sets installed.
科研人员又将一颗卫星平安地送上了太空。
The scientists have succeeded in launching another satellite.
安定【ān dìng】
1. quiet; settled; stable; calm and orderly 2. stabilize
[形]1、（生活、形势等）平静、正常、稳定 [动]2、使安然、稳定
他放弃了原先安定的工作，开始自己创业。
He gave up a stable job and set up his own business.
在国外安定下来后，他开始想念家乡的父母了。
He came to miss his parents back at the home after he had settled down abroad.
建设一个环保的城市，是为了让子子孙孙能够安家立业。
是否应该施行安乐死，引起了人们广泛的讨论。
边境地区总是不太安宁，经常发生战争。
老人操劳了大半生，想早点退休过几天安宁日子。
今天晚上我不能陪你去看电影了，我有其它的安排。
为了大家的安全，我们等天亮后再出发吧。
