下列各组字母中含有相同读音的一组是 ____.

I want to go to the party, but ______I ought to be studying[ ]

I got a letter this afternoon. It was ____my foreign friend.

When the man with a scar came into the café I noticed a ______ look come over the waitress face although she did not say anything.

The girl is so helpful that she devoted all her spare time she had ______ others.