Insert articles where necessary:
1. This is __ cat. It's Tom's ____ cat.
2. Is this your ___ bag? No, this is not my ___ bag. It's Nick's bag.
3. I have no ___ sugar in my ___ tea.
4. I have ____ flat. My____ flat is comfortable. There are three ____ rooms in ___ flat. 5.____ door is locked. Where is ____ key?