2. Write I, he, she, it, we or they.

Solution:

1. 'Are you ten?' 'Yes, I am.'
2. 'Is this a pen?' 'Yes, it is.'
3. 'Where is Mark?' 'He is in the garden.'
4. 'Is Lily five?' 'No, she isn't.'
5. 'Are you and Anne sisters?' 'No, we aren't.'
6. 'Are these snakes?' 'Yes, they are.'