1. 1a, 2a, 3a
2. 1 is, 2 are, 3 are, 4 is
3. 1 is (There isn't a chair at the table. Is there a chair at the table?) 2 are (There aren't books on the shelf. Are there books on the shelf?)
4. 1is 2rooms 3 Yes, there is 4 are
5. There is a bid table in the room. There is a pen on the table. There is a ball under the table.