1. To be undecided or skeptical about:
began to doubt some accepted doctrines.
2. To tend to disbelieve; distrust:
doubts politicians when they make sweeping statements.
3. To regard as unlikely:
I doubt that we'll arrive on time.
4. Archaic To suspect; fear.
5. To be undecided or skeptical.
7. A lack of trust.
8. A point about which one is uncertain or skeptical:
reassured me by answering my doubts.
9. The condition of being unsettled or unresolved:
an outcome still in doubt.
10. Without question; certainly; definitely.
13. Middle English douten
14. from Old French douter
源自 古法语 douter
15. from Latin dubit3re [to waver] * see dwo-
源自 拉丁语 dubit3re [犹豫不决] *参见 dwo-
16. Doubt and doubtful may be followed by clauses introduced by that, whether, or if. The choice among these three is partly guided by the intended meaning of the sentencebut is not cast in stone. Whether normally introduces an indirect question and is therefore the traditional choice when the subject is in a state of genuine uncertainty about alternative possibilities:
Doubt 和 doubtful 后面可以跟由 that，whether， 或 if 引导的从句。 三者之间选哪一个部分地由句子要表达的意义决定的，但其用法并不是固定不变的。Whether 一般引导一个间接问句，所以当主语所代表的人确实不知如何选择判断时，传统上就用该词：
Sue has studied so much philosophy this year
17. that she's begun to doubt whether she exists.
At one time it was doubtful whether the company could recover from its financial difficulties, but the government loan seems to have helped.
18. On the other hand, that is the choice when doubt is being used as an understated way of expressing disbelief:
而当doubt 用来低调表示“不相信，不信任”之意的时候，则用 that 。
I doubt that we've seen the last of that problem (with the meaning “I think we haven't seen the last . . . ”).
我不相信我们完全解决了那个 问题 （意即：我认为我们没解决那个问题）。
19. That is also the usual choice when the truth of the clause following doubt is assumed, as in negative sentences and questions. Thus I never doubted for a minute that I would be rescued implies “I was certain that I would be rescued.” By the same token, Do you doubt that you will be paid? seems to pose a rhetorical question (“Surely you believe that you will be paid”), whereas Do you doubt whether you will be paid? may express a genuine request for information and might be followed by because if you do, you should make the client post a bond. In other cases, however, this distinction between whether and that is not always observed, and that is frequently used as a substitute for whether. If may also be used as a substitute for whether but is more informal in tone. · In informal speech the clause following doubt is sometimes introduced with but: I don't doubt but (or but what ) he will come. Reputable precedent exists for this construction, as in “I do not doubt but England is at present as polite a Nation as any in the World” (Richard Steele), but modern critics sometimes object to its use in formal writing.See Usage Note at but, if
在否定句及疑问句中当doubt 后的从句所作陈述被认为是真时，用 that 。 所以我从不怀疑我会被救起 意思就是“我确信我会得救”。 同样你怀疑人家会赖帐吗？ 似乎就成了一个反问句（“你当然相信人家不会赖帐了”）， 而你怀疑人家是否付款吗？ 就表示一个真诚的询问， 可能接下来会说因为如果你怀疑的话，你就该让顾客付保证金 。 在其它情况下，whether 和 that 的区别并不很明显， 而且that 经常用来替代 whether。 If 也经常用来代替whether ， 但是语气不很正式。在非正式语气中doubt 后面的从句有时由 but引导：I don't doubt but （或 but what ) he will come。 这种结构有其先例且属规范用法，如“我不怀疑目前的英格兰象世界上其他国家一样是礼义之邦” （理查德·斯蒂尔），但现代评论家有时反对在正式文体中这样使用参见 but， if