
Keep a close eye/watch on somebody/something
Surveillance Metaphor
The phrase implies careful monitoring, as if keeping something within sight at all times.

The security guard kept a close watch on the entrance during the event.
Attention to Detail
It suggests focusing on small details or changes to prevent problems or notice opportunities.

She keeps a close eye on her investments to catch any market changes quickly.
Not Literal
It's often used figuratively. You don't need to literally watch something, but to stay informed about it.

I'll keep a close eye on the weather forecast for our trip.
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