allow,permit,let,promise
允许、许可、答应
allow vt."允许、准许"，含有“不阻止、不反对”的意思，侧重“听任、默许”，含有消极的不反对的意思。
Mr.Hornsnagle,an American news reporter,asked the ruler of Yap Yap whether free speech was allowed under his rule.
Allow me to introduce them to you.
Smoking is not allowed here.
permit vt.&vi.“许可、容许”，可与allow通用，但含有积极的从正面给予允许的意思。比allow正式，且语气较强。
"Mr.Crossett,"said my father ,"Will you permit an old pupil to shake hands with you?"
let vt."让、允许"，意思与allow和permit相同，但比较口语化，它的宾语后必须连用不带to的动词原形，同时它不能用于被动语态。
I will let you choose how you're going to die.
promise v.&n."答应、允诺"表示主语自己保证或允许要做什么，而不是允许别人做什么。
During the third hundred years,I promised that if anyone came to set me free,I would make him king over the earth.
I do not want you simply to promise me with words that you will be good but I want you to show me with your heart that here we are all part of one big family.
