doubt /daut/ I. n. ［u］ & ［c］ 1.怀疑，疑虑：arouse doubts 引起怀疑；cast doubts/a doubt on/upon … 对…产生怀疑；throw doubt upon one’s word对某人的话产生了怀疑 2.用于短语in doubt 存在怀疑的：The outcome is no longer in doubt.结果已毋庸置疑。make no doubt 对…毫不怀疑；一定要确定：I make no doubt of it. 我对此毫不怀疑。Make no doubt that the door is locked. 一定要检查一下确保门已锁好。 no doubt 肯定地，想必：No doubt it is very absurd. 这无疑是很荒谬的。‖II.vt. & vi.怀疑，不相信：You are doubting me unjustly. 你在不公正地怀疑我。There’s no reason to doubt of his ability. 没有理由怀疑/不相信他的能力。

［辨析］doubt后要跟whether或if从句，表示 “怀疑”，但在否定句中就表示“不怀疑”，一定要跟that从句。suspect 表示“疑有”，含有较强的肯定意味，因此要跟that从句。

 

doubtful /ˈdautfəl/ adj. 怀疑的，犹豫的，难以预测的：That’s rather doubtful. 那件事颇为可疑。The weather looks very doubtful. 天气看上去很靠不住。I feel doubtful about whether to go. 是否要去，我犹豫不决。Are you doubtful of Mr. James? 你对詹姆斯先生有怀疑吗? 

 

doubtless /ˈdautlis/ adv. 无疑地， 肯定地： He is doubtless respectable. 他无疑是可敬的。 He will doubtless come on time.他肯定会准点来到。