You must be mistaken.
你一定搞錯(cuò)了。
must的意思是“必須”,比如下命令時(shí)老板有時(shí)會(huì)很強(qiáng)硬地說(shuō),
"You must finish this book before this weekend."
(你必須在周末前完成這本書(shū)。)
在下面的這句話(huà)里must的意思有些變化,有了很強(qiáng)的推測(cè)語(yǔ)氣,
"He must have passed the exam, because he was so happy the whole day."
(他一定已經(jīng)通過(guò)考試了,因?yàn)樗於寄敲锤吲d。)