Allow, let, permit 允许；许可；准许
Permit比allow 要正式，allow比let要正式。
Permit 尤指根据正式决定、规章或法律允许做某事
Smoking is not permitted in this hospital.
这家医院不允许吸烟。
Allow 某人（家长、老师等）准许做某事
His parents allowed him to play with his classmates after school.
他的父母允许他放学后和同学们一起玩。
Let 让；允许做某事（常用于日常口语中）
Let me show you how to operate it.
我来教你怎么操作。
1.Permit/allow sb to do sth 允许某人做某事
Photography is not permitted inside the museum.
博物馆内不准摄影。
Her parents won't allow her to marry him.
她父母不允许她嫁给他。
His father will not allow him to go there alone.
他父亲不允许他一个人去那里。
2.let sb do sth 让某人做某事
Let me check it first.
让我先检查一下。
Let's have a try.
我们试试看。
I will not let you go.
我不会让你走的。
3.permit和allow可以用于被动语态；let不用于被动语态
We are not permitted to bring our cameras and cell phones.
我们不允许携带照相机和手机。
Students are not allowed to cheat during the exam.
考试期间不准学生作弊。
Students are not let cheat during the exam. (X)
