All 4 are grammatically correct.
The first two are close, but don't mean exactly the same thing. In #1, it isn't clear if he started playing when "I" entered or if he had already been playing and then he continued.
1. When I entered the room, he played the piano.
2. When I entered the room, he started to play the piano.
(Is #1 grammatical? Is #1 similar to #2?)
3. When I entered the room, he had been playing the piano for an hour.
4. When I entered the room, he was playing the piano.
(Are both grammatical?)
1 answer
2 answers