1. On top of indicates a position higher than the object.
Pattern: verb + on top of + noun
They put the blanket on top of the sheets, and the bedspread on top of the blanket.
I’m sure I left my keys on top of the desk.
2. Expression
to be on top of something—to be sure about one's knowledge or control of something Her son had a hard time learning math, but he is on top of it now.
Fact
In Ohio, if you ignore an orator on Decoration day to such an extent as to publicly play croquet or pitch horseshoes within one mile of the speaker's stand, you can be fined $25.00.
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