1) Are you certain / sure ? 你能肯定吗 ？
2) Are you sure / certain about the result ? 你对结果有把握吗 ？
3) There is no doubt about it . 这是毫无疑问的。
4) I\'m one hundred percent certain . 我百分之百地肯定。
5) I\'m sure of heavy rain in the afternoon . 我确信今天下午要下大雨。
6) I\'m certain that it\'ll snow this evening . 我敢说今天晚上会下雪。
7) I have no doubt about it 对此事我敢肯定。
8) It\'s hard to say . 这很难说。
9) I can\'t decide . 我拿不定主意。
10) There\'s a chance that a cure will be found for cancer . 治疗癌症的方法可能会找到。
11) No one can say for certain that the method will soon be found . 没有人能肯定说方法会很快找到。
12) I\'m sure that he\'ll succeed . 我肯定他能成功。
13) We\'re not sure whether we\'ll win the game . 能否赢这场比赛，我们不太有把握。
14) He doubts if that is you want . 他不知道那是否是你要的东西。
15) I\'m quite (dead , absolutely ) sure / certain he\'s living in Beijing . 我绝对肯定他住在北京。
16) This conference will be a success , I\'m sure . 会议会成功的，我肯定。
17) That must / can\'t be the right way . 这条路肯定（不可能）对。
18) They must have taken the short cut . 他们肯定抄近路了。
19) He may / might be there . 他可能在那儿。
20) Yes , certainly . / No , certainly not . / Yes , it sure / certainly is . / No , it certainly isn\'t .
21) Yes , no doubt at all . / Yes , without a doubt . 对， 毫无疑问。
22) Not a hope . 不可能。/ No chance at all . 一点也不可能。
23) There\'s very little doubt that we\'ll have the order tomorrow . 我们明天拿到定单没有什么疑问的。
24) We do not doubt that he is honest . 我们并不怀疑他是一个诚实的人。
25) It\'s certain ( obvious , clear , plain ) that he will win the game . 很明显我们队将在这场比赛中获胜。
26) It\'s certain ( obvious , clear , plain ) that he\'s suffered a great deal . 很明显他蒙受了极大的痛苦。
27) Without doubt , she is one of the best teachers in the school . 不可否认，她是该校最优秀的教师之一。
28) I can\'t say for certain , but I think ( have a feeling , have an idea ) he might be from the States . 我不能肯定，但我觉得（猜想）他也许是从美国来吧。
29) I\'m afraid I can\'t know ( make up my mind ) which one to buy . 恐怕我不能决定买那个好。
30) It seems clear to me (pretty obvious) that we are getting lazy in our old age . 人老了渐渐懒惰起来，这一点在我看来是很清楚的。
31) Can you really be sure of his honesty ? 你真的能确信他的诚实 ？
32) You are sure he will get the first prize ? 你能肯定他会得一等奖 ？
33) Do you think you have no doubt of his arrival in time ? 你认为他无疑会按时到达吗 ？
34) Forgive me , but are you really certain ? 对不起，不过你真的能肯定吗 ？
35) There\'s no doubt in your mind about his aim ? 对他的目的你心里不存疑虑吧 ？
36) He must be there in the kitchen . 他一定是在厨房里。
37) He will certainly die if you don\'t get a doctor now . 如果你现在不请医生他一定会死的。
38) I bet . 我敢断定。/ I bet he\'s been back now . 我敢打赌他已回家了。
39) There\'s no room for doubt about it . 此事无可怀疑。
40) I\'m in two minds about which to choose . 我决定不了挑选哪个好。