反過來說，不合理的英文形容詞就是在 reasonable 前面加上 un 代表反的意思，寫成 unreasonable（聽發音）這樣，舉例來說，不合理的要求英文是 unreasonable demand 或 unreasonable request、不合理的制度是 unreasonable system。
合理英文造句練習
Your proposal is very reasonable, so the company decided to adopt.你的提案非常合理，所以，公司決定採用。
The pay of this company is very reasonable, you can think about it.
這間公司的薪資給得很合理，你可以考慮看看。
This story compiled too unreasonable, no wonder no one believed.
這個故事編得太不合理了，難怪沒人相信。
The price of this dress is very reasonable, like it can buy.
這件衣服的價格很合理，喜歡的話可以買。
Jack's explanation was very reasonable, so the mother is willing to forgive him.
傑克的解釋非常合理，所以，媽媽願意原諒他。
The principle of user fees is very reasonable.
使用者付費這個原則非常合理。
The price of good performance car more expensive is reasonable.
性能好的車子的價格較貴是合理的。
If you want others to use your plan, then you have to put forward a reasonable solution.
如果你要別人採用你的計畫，那你就要提出一個合理的方案。
Anything should be reasonable.
任何事情應該都要合理。
This task is not reasonable.
這的任務並不合理。
The registration of this activity is simply unreasonable.
這項活動的報名辦法根本不合理。
This ticket is unreasonable and Mike intends to appeal.
這個罰單不合理，麥克打算申訴。（ticket 是票券的意思，在這裡是指罰單）
Do you think this document is reasonable?
你覺得這份文件合理嗎？
Our boss thinks there are several items in the contract that are unreasonable.
我們的老闆認為這份合約內有幾個項目不合理。
If you think the other side of the proposed solution is unreasonable, you can also put forward your idea.
如果你覺得對方提出來的方案不合理，你也可以提出你的想法。
Mike and Mark find a reasonable negotiation model.
麥克與馬克找到一個合理的談判模式。
The design logic of this program is unreasonable, so there are a lot of mistakes.
這個程式的設計邏輯不合理，所以出現了很多錯誤。
Teachers should adopt a reasonable way of education.
老師應該採用合理教育方式。