1. He appeared on the stage.

2. He disappeared from the stage.
3. He disappeared on the stage.
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What is the opposite expression of #1?

if you want to say he left the stage then your answer should be

"He disappeared from stage"..... else both are correct with different meanings..

He disappeared from the stage, This is the right answer

1 and 2 are fine.

3 is not used.

The opposite expression of "He appeared on the stage" would be "He disappeared from the stage."