OK,I'll keep my eyes open中的"keep my eyes open"什麽意思

问题描述:

OK,I'll keep my eyes open中的"keep my eyes open"什麽意思
一到英语智力题:
---Do you know that man?
---Yes,he works near here.
---Would you tell me when he comes here?
---OK.I'll keep my eyes open.
最后一句中的"keep my eyes open"有什么特殊意思?

我会始终保持清醒