An unforeseen event is one that nobody expected to happen. The rain that ruined the outdoor wedding, the illness that emptied half the office, the delay that pushed the opening back a month.

An unforeseen event無法預料的事is one that nobody expected to happen就是沒有人預期會發生的事：The rain that ruined the outdoor wedding毀了戶外婚禮的雨、the illness that emptied half the office讓辦公室半數人請假的病、the delay that pushed the opening back a month把開幕延後一個月的延誤。

In practice you meet it most in a small set of fixed phrases: unforeseen circumstances, unforeseen problems, unforeseen difficulties, unforeseen consequences, unforeseen delays, unforeseen costs.

In practice實際上，you meet it most最常見到這個字出現in a small set of fixed phrases在幾個固定詞組裡：unforeseen circumstances不可預料的情況、unforeseen problems不可預料的問題、unforeseen difficulties不可預料的困難、unforeseen consequences不可預料的後果、unforeseen delays不可預料的延誤，還有unforeseen costs不可預料的花費。

'Due to unforeseen circumstances' is one of the most useful phrases in polite English — it is what a shop puts on the door when it closes suddenly, what an organiser says when an event is cancelled. It explains without explaining, which is exactly why people use it: it is a graceful way to say something went wrong without telling you what. Almost always the event is a bad one.

'Due to unforeseen circumstances'「因不可預料的情況」這句話is one of the most useful phrases in polite English是禮貌英文裡最好用的說法之一——it is what a shop puts on the door when it closes suddenly是店家臨時關門時貼在門上的話，what an organiser says when an event is cancelled也是主辦單位取消活動時會說的話。It explains without explaining它解釋了卻又沒真的解釋，which is exactly why people use it這正是大家愛用它的原因：it is a graceful way to say something went wrong without telling you what是一種優雅的說法，可以說出事情出了差錯，卻不必說是什麼差錯。Almost always the event is a bad one而幾乎每次，這裡的事都是壞事。

You can say 'unforeseen benefits' and be understood, but the word carries trouble with it, so unforeseen good news sounds slightly odd.

You can say 'unforeseen benefits'你可以說「意外的好處」and be understood別人也聽得懂，but the word carries trouble with it但這個字本身帶著麻煩的味道，so unforeseen good news sounds slightly odd所以「意外的好消息」聽起來會有點怪。

Grammatically, it nearly always sits in front of a noun. We say 'unforeseen problems'; we do not usually say 'the problems were unforeseen', though it is not wrong.

Grammatically文法上，it nearly always sits in front of a noun它幾乎都放在名詞前面：We say 'unforeseen problems'我們會說「unforeseen problems」，we do not usually say 'the problems were unforeseen'但通常不會說「the problems were unforeseen」，though it is not wrong雖然這樣說也沒有錯。

It is moderately formal — comfortable in a letter, a notice, or the news, a little heavy for chatting with friends, where you would say 'something came up'.

It is moderately formal這個字算是稍微正式，comfortable in a letter, a notice, or the news用在信件、公告或新聞裡很自然，a little heavy for chatting with friends但用在朋友聊天就有點重，where you would say 'something came up'那種場合你會說「something came up臨時有事」。