- a feeling of uncertainty or lack of conviction不确定, 疑惑, 怀疑, 疑虑：
some doubt has been cast upon the authenticity of this account
人们对这一报道的真实性产生了某种怀疑
count noun they had doubts that they would ever win.他们对自己能否获胜曾产生过怀疑。
- with obj. feel uncertain about不能肯定, 对…没准儿：
I doubt my ability to do the job.
我对自己是否有能力做这工作没有把握。
- question the truth or fact of (something)怀疑, 对…有疑问：
who can doubt the value and necessity of these services?
谁能怀疑这些服务的价值和必要性？
with clause I doubt if anyone slept that night.我怀疑那天夜里是否有人睡过觉。
- disbelieve (a person or their word)不相信：
I have no reason to doubt him.
我没有理由不相信他。
- no obj. feel uncertain, especially about one's religious beliefs（尤指对自己的宗教信仰）不肯定; 怀疑。
- with clause Brit. archaic fear; be afraid〈英, 古〉害怕; 恐怕; 担心：
I doubt not any ones contradicting this.
我不担心有人反对这一点。
beyond doubt
- allowing no uncertainty无疑地, 确实地：
you've proved it beyond doubt.
毫无疑问, 你已证明了它。
in doubt
- open to question可怀疑的, 存在疑问的：
the outcome is no longer in doubt.
结果已毋庸置疑。
- feeling uncertain about something不能肯定的, 不确定的：
by the age of 14 he was in no doubt about his career aims.
他14岁时就确定了奋斗目标。
no doubt
- used to indicate the speaker's firm belief that something is true even if evidence is not given or available无疑地, 确实地, 我确信：
those who left were attracted, no doubt, by higher pay.
毫无疑问, 那些离去的人是受了高薪的吸引。
- used to introduce a concession which is subsequently dismissed as unimportant or irrelevant很可能, 或许：
they no doubt did what they could to help her, but their best proved insufficient.
他们或许尽力帮助了她, 但还不够, 他们没有全力以赴。
without (a) doubt
- indisputably毋庸置疑地：
he was without doubt the very worst kind of reporter.
毋庸置疑, 他属于那种最糟糕的记者。