一 . 如果后面接名詞、代詞或名詞性詞組時，兩者基本上可通用。

例如：I doubt/suspect the truth of her statement. 我對她那番話的真實性表示懷疑。He says he can cure me， but I still doubt/suspect him. 他說他能治好我的病，但我仍對他不放心。二 . 如果后面接 that 從句，意思就截然不同。 doubt 意為“無把握；不相信（ question the truth of； don't believe/think ）”，懷疑其無。 suspect 意為“有存在或?qū)賹嵉南敕?；相信?have an idea of the existence； believe； guess ）”，懷疑其有。例如：I doubt that he has stolen my watch.我不相信他偷了我的手表。I suspect that he has stolen my watch.我懷疑 / 猜想他偷了我的手表。The doctor suspected that he was ill with flu.醫(yī)生懷疑 / 認為他得了流感。這時 doubt 更多用于否定句或疑問句中。如：I don't doubt that he is right. 我確信他是對的。I didn't doubt that he would come. 我當時相信他會來的。Why did she doubt that they were cheats？她為什么懷疑他們是騙子？三 . doubt 用于肯定句中時，多接 whether/if 引導的從句，意義與 that 從句不同，這時意為“不敢肯定（ feel uncertain about ）”。而 suspect 不可接這種從句。例如：I doubt whether/if he'll come. 我不敢肯定他來不來。It's raining hard. I doubt whether it will be fine tomorrow.雨下得很大，我不敢說明天會晴。四 . 其他搭配。doubt 可作不及物動詞，用于 doubt of sth； suspect 用于 suspect sth to be， suspect sb of（doing） sth .例如：She never doubted of his success. 她從不懷疑他的成功。I suspected him to be the spy. 我認為他就是那個間謀。What made you suspect her of having taken the money？你憑什么懷疑錢是她偷的？