---Are the Smiths living in the house alone ?--- Yes, although they have three sons, _____ of them live with their parents.
We must try our best to stop the pollution a happy life.
John’s never flown to Canada, ?
He hasn’t got a letter from his uncle .
It is _____ unlucky day today. I’ve lost _____ useful pen.
Can you help me? I have trouble _____ the story in English.