I'm at a loss what to do next.

我对下一步做什么心里没谱。

《牛津词典》

He was unsure of what to do next.

他对下一步该做什么犹豫不定。

《牛津词典》

I was at a loss for what to do next.

我不知道下一步该怎么办。

《柯林斯英汉双解大词典》

Second,law enforcement has to have a seat at the table when we talk about what to do next.

VOA: standard.2010.08.11

So one way that neurons, in particular, are able to communicate with other cells in the nervous system, share information, integrate information, decide what to do next is that they are physically connected to other different cells.

所以神经细胞之所以能够,与神经系统中其他细胞通讯,分享信息,整合信息,从而决定下一步该做什么,是由于不同细胞间,是彼此连接在一起的

耶鲁公开课 - 生物医学工程探索课程节选

Let's say you're having a conversation about what to do next during the day.

假设你正在讨论第二天应该做点什么。

It depends on 课堂 - SpeakingMax英语口语达人

While figuring out what to do next, she held a garage sale to de-clutter her house.

WSJ: Ki Nassauer, Envisioning Treasures From Piles of Junk | Creating

The most striking parts of the general's testimony were his recommendations for what to do next.

ECONOMIST: America and Iraq

The administration also appears to be in a quandry about what to do next.

CNN: Kelly Wallace is a CNN White House correspondent.