I am optimistic that we are going to be able to manage this effectively, but we still have more work to do, and I am glad I have got such a great team doing it,"

VOA: standard.2009.05.01

All right, so I'm going to be optimistic.

好了，我现在乐观假设。

耶鲁公开课 - 死亡课程节选

I think you need to be more optimistic.

我觉得你需要更乐观一点。

There is 实战 - SpeakingMax英语口语达人