It's a waste of money.

It is wasted effort.

to be wasted

Watch my camera for a moment, please.

My watch is fast.

Watch your mouth!

My watch is slow.

Watch out for tricksters!

to watch someone/something like a hawk

to watch someone’s every move

to watch someone’s every step

By my watch it’s five to twelve

On my watch, it's two o'clock.

My watch loses.

My watch gains.

My watch is wrong

My watch shows the date.

Watch out for thieves!

Watch out for pedestrians, please!

to watch narrowly

to watch for certain symptoms

to watch children

to be on a watch

to watch with interest

We watch TV together.