There is a mistake in each sentence. correct the mistakes. 1. actors may learn a lot of dialogues by heart. 2. your glass is empty. must i refill it? 3. would i introduce mr. brown to you? 4. my sister can to play a few musical instruments. 5. some years ago i didn’t can speak english.

1. Actors must learn a lot of dialogues by heart.
2. Your glass is empty. Shall I refill it?
3. May I introduce Mr. Brown to you?
4. My sister can  play a few musical instruments.
5. Some years ago I couldn't speak English.