THE or 0 ?

1- What is the capital of United Kingdom?
2- He lives in Germany, doesn't he?
3- My best friend is quite musical : he plays flute very well.
4- I don't play football but I belong to a rugby team.
5- My uncle and aunt visited Netherlands last year.
6- Jazz musicians often play sax and trumpet, don't they?
7- I think that basketball is one of the most popular sports in England and in USA.
8- Don't you think that skiing can be quite dangerous?