1. Are you inviting Tom to dinner? Yes, I am.
2. Is she knocking at the door? No, she isn't.
3. Is Peter going to the station? Yes, he is.
4. Is the secretary typing the letters? No, he / she isn't.
5. Is Ann taking the bus today? Yes, she is.
6. Is Susan enjoying the concert? No, she isn't.
7. Are you hearing this? Yes, I am.
