keep (your)/an eye on (something/someone)

to watch or look after something or someone.

Could you keep an eye on the baby for me a while?

I kept my eye on him all the time as I felt sure he was about to do something stupid.

• on demand
• on doorstep
• on duty
• one after the other
• one and all
• one and the same
• on earth
• one day
• one-day wonder
• on edge
• one for the books
• one for the road
• One good turn deserves another.
• one-hit wonder
• one-horse race
• one-horse town
• one-man band
• One man's meat is another man's poison.
• on end
• one-night stand
• one of a kind
• one of the boys
• one of the lads
• one of those days
• one-shot