如何区分before和after~有时候觉得两者可以通用我找到一些相对以上更容易看得出before：1、主句动作发生之前，从句动作发生在后Turn off the light before you leave the room2、“.....之后（才）”主句

如何区分before和after~有时候觉得两者可以通用
我找到一些相对以上更容易看得出
before：1、主句动作发生之前，从句动作发生在后
Turn off the light before you leave the room
2、“.....之后（才）”主句动作在从句之前完成，故主句常用过去完成时
The mother had waited for half an hour before her son came back。
我现在需要类似以上的答案是关于after

after
prep.（介词）
Behind in place or order:
在之后：在地方或顺序之后：
Z comes after Y.
Z在Y之后
Next to or lower than in order or importance.
次于：在顺序或重要性上次于或低于
In quest or pursuit of:
探求,追求：
seek after fame; go after big money.
追逐名誉；追求钱财
Concerning:
有关,关于：
asked after you.
询问关于你的情况
Subsequent in time to; at a later time than:
在…以后：时间上在…之后；比…晚一点：
come after dinner.
晚饭之后来
Subsequent to and because of or regardless of:
随后因为,随后不管：
They are still friends after all their differences.
尽管有许多相异,他们依旧是朋友
Following continually:
一个接一个：持续不断地紧接着：
year after year.
年复一年
In the style of or in imitation of:
依照,仿照：以…的风格或模仿…：
satires after Horace.
模仿贺拉斯的讽刺作品
With the same or close to the same name as; in honor or commemoration of:
纪念,以…命名：与…名字有相同或相近的名字；为纪念…：
named after her mother.
以他母亲的名字命名
According to the nature or desires of; in conformity to:
与…一致：根据…的本质或愿望；与…一致：
a tenor after my own heart.
深得我心的内容
Past the hour of:
…点以后：
five minutes after three.
三点过五分
adv.（副词）
Behind; in the rear.
在后；在后面
At a later or subsequent time; afterward:
接着,以后：在后来或接下来的时间；以后：
three hours after; departed shortly after.
三小时以后；不久就离开了
adj.（形容词）
Subsequent in time or place; later; following:
以后的,接着的：在时间和地点上继后的；以后的；接下来的：
in after years.
在以后的岁月里
Nautical Nearer the stern of a vessel.
【航海】 靠近船后部的
conj.（连接词）
Following or subsequent to the time that:
在…之后：紧接或继…之后：
I saw them after I arrived.
在我抵达之后,我见到了他们
n.（名词）
Afternoon.
下午,午后
before
adv.（副词）
Earlier in time:
在此之前：早些时候：
They called me the day before.
前一天他们给我打了电话
In front; ahead.
在…前面；在前头
prep.Abbr.bef.（介词）缩写 bef.
Previous to in time; earlier than.
…之前：在…时间之前；早于…
In front of.
在…前面
In store for; awaiting:
即将发生的；等待着的：
A young person's whole life lies before him.
年轻人的生命展现在他前面
Into or in the presence of:
进入,在…面前：
She asked that the visitor be brought before her.
她要求把访问者带到她的面前来
Under the consideration or jurisdiction of:
在考虑中,在审理中：
The case is now before the court.
这个案子现在已交庭审理
In a position superior to:
地位高于：
The prince is before his brother in the line of succession.
在王位继承权上,这个王子优于他兄弟
conj.（连接词）
In advance of the time when:
在…时间之前：
See me before you leave.
在你离开之前来见我
Rather than; sooner than:
宁可…也不愿；与其…宁可：
I will die before I will betray my country.
我宁可死也不会背叛我的国家

before 是在。。。。之前
after 是在之后

before
[bi5fC:]
adv.
在前, 以前
prep.
在...之前
conj.
在...之前, 与其...宁可
after
[5B:ftE]
adv.
prep.conj.在...之后, 在...后面, 模仿, 与...一致, 以...命名, 后来的, 后面的

could you please state some instance about the similarity of \"before,and after\"
then i can give you a exact answer