to do wonders (for) = to be surprisingly beneficial to someone or something; to be very helpful with someone or something.

I was run out and drained of energy, but a week of complete rest did wonders for me.

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to do the donkey work = to do the hard, boring part of work or manual tasks

Why is it always me who does the donkey work in the office?

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to do something with one’s eyes closed = to do something easily because you have done it many times

– Show you around the town? – I could do it with my eyes closed!

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to do someone a good turn = to help someone

One good turn deserves another. = If someone has helped you, help them in return.

You did me a good turn when I was in trouble, now I owe you one.

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to do more harm than good = to be damaging rather than helpful

I am afraid that studying till morning will do you more harm than good.

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