Грамматика в британском "A" и "The" в предложенияхГде пишется "A" а

Грамматика в британском "A" и "The" в предложениях
Где пишется "A" а где "The"
He met girl at the disco. girl was a wonderful dancer.
My uncle built a new house. house is small but rather comfortable.
There is ...new dictionary on sale now. ..dictionary gives 200,000 words.
I saw beautiful dress in shop, but dress was too expensive for me to buy it.
You asked me question but I think you should know answer yourself.