You are making a big mistake.

　　你正在犯一個嚴(yán)重的錯誤。

　　It's all been a ghastly mistake.

　　這是個極其惡劣的錯誤。

　　She paid dearly for her mistake.

　　她因犯錯誤而付出了巨大的代價。

　　The engagement was a bad mistake.

　　這婚約是一項大錯。

　　He was loath to admit his mistake.

　　他不愿承認自己的錯誤。

　　I made a stupid mistake.

　　我犯了個愚蠢的錯誤。