1. Are you certain about that? 你确定吗?
2. Were you quite sure about your success? 你有把握你能成功吗?
3. Really? 真的吗?
4. I suppose you have no doubt about that. 我想你对那件事毫无疑问吧。
5. I've no doubt of your ability. 我对你的能力没有怀疑。
6. I bet they've got lost. 我敢断定他们迷路了。
7. I'm quite convinced things will improve. 我确信事情会好转的。
8. It's hard to tell. 很难说。
9. That's my conviction. 这是我的信念。
10. I can't decide when to start. 我不能决定什么时候出发。