最近修訂《英文的對與錯》一書，其中有個例子：「他的行為令人不能容忍。」His conduct is simply intolerable.
讓人想起王爾德的名言：「流行就是一種醜到令人不能忍受的款式，所以每六個月得改換一次。」
Oscar Wilde 在 The Philosophy of Dress 一文中提出 “Fashion is ephemeral, Art is eternal.” (流行是短暫的，藝術是恆久的。) … A fashion is merely a form of ugliness so absolutely unbearable that we have to alter it every six months!” 的驚世論點。(New-York Tribune, April 19th, 1885, 9 [1])
之後他在主編 The Woman's World 的編輯札記裡又重述同樣的觀點，不過「不能忍受的」一詞從 unbearable 換成 intolerable：
"And, after all, what is a fashion? From the artistic point of view, it is usually a form of ugliness so intolerable that we have to alter it every six months."
(The Woman's World. November 1887. pp 36-40)
Intolerable 有時也可譯為「難受的」、「受不了的」。例如：intolerable heat (熱得受不了/熱得難受) 等。
Intolerant 也是「不能忍受的/不能容忍的」，但主要用於指人心胸褊狹或人對食物過敏、不耐、排斥等狀況。例如：
He was intolerant of both suggestions and criticisms.
He was so firm in his own belief that he was intolerant of others’ opinions.
(不能容忍別人的批評、意見)
Can you still have dairy if you are lactose intolerant? (如果對乳糖不耐，還能食用乳製品嗎？)
簡單地歸納：
intolerable 主要用於指較抽象的事物，如：行為 (conduct)、粗魯 (impudence) 惡臭 (stench)、冷熱、醜陋，讓人不能忍受。intolerable 常與介系詞 in 搭配，主詞通常為事物。 This is intolerable in a free society.
intolerant 用來指人，如人排斥批評、建議或某些食物—wheat, gluten (麩質), dairy, lactose, peanuts, seafood 等。Intolerant 常與 of 搭配，主詞通常為人。 Some people are so intolerant of homosexuality….
(Jerome Su, August 26, 2020, Expanded August 28)