同义词是certain，同义短语是of course，例如：

1.Certain of those present were unwilling to discuss the matter further.某些在场的人不愿意进一步讨论这个问题。

此处答案分享如下：sure的同义词是certain

"Sure"的一些同义词包括: 1. certain2. positive3. confident4. definite5. assured6. convinced7. unquestionably8. undoubtedly9. undeniably 10. secured