| 短语 | 使用场景 | 例句 |
| Be certain | 日常对话中表示确定 | I'm certain he will come.（我确信他会来。） |
| Be sure | 表达自信或确定 | I'm sure we can finish it on time.（我确信我们能按时完成。） |
| There's no doubt that... | 强调事实无可置疑 | There's no doubt that she is the best candidate.（毫无疑问，她是最佳人选。） |
| Confirm that... | 验证信息或事实 | Please confirm that the meeting is still scheduled for tomorrow.（请确认会议仍定于明天进行。） |
| Without a doubt | 强烈肯定 | Without a doubt, this is the best decision we've made.（毫无疑问，这是我们的最佳决定。） |
| Absolutely | 强调肯定程度 | I absolutely agree with you.（我完全同意你的观点。） |
| Undoubtedly | 正式场合常用 | Undoubtedly, the project will be successful.（毫无疑问，这个项目会成功。） |
| Definitely | 日常口语中常用 | I definitely need to go now.（我肯定得走了。） |
| Guarantee that... | 承诺或保证 | I guarantee that the product will work as described.（我保证产品会按描述工作。） |
| Obviously | 表达显而易见的事 | Obviously, the answer is no.（显然，答案是否定的。） |