TheBlackDiamond What is the capital of Great Britain? London is the capital of GB, is not it?  Is London the capital of GB?  Is London the capital of GB or is London the capital of France?  
When they were in the forest? They were in the forest last week, were not they? Were they in the forest last week? Were they in the forest last week or they were in the forest last month?
Who is my sister? Is my sister a student? My sister is a student, is not she? Is my sister a student is she a writer?