Question

1. He skipped stones over the lake.
2. He skipped stones on the lake.
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When the stones are jumpping on the surface of the water, what preposition can we use?

Answer 1

We would say "on the lake", but either is correct.

Answer 2

Thank you for your help.
What about 'across'?

3. He skipped stones across the lake.

Answer 3

That, too, is acceptable.