Ответ:
1) The channels are devoted to more specialized topics.
2) My Mum has been doing aerobics for a year and she looks great.
3) The Britons have used double-deckers for hundreds of
years.
4) My friends has won/won a competition.
5) She has been reading the book since morning.
6) They have been watching the talk show for an hour already,
7) Jack has just arrived home.
8) He has been travelling around the world since July.
9) The train has already arrived already at the station.
10) Tom didn't go to the language courses last week.
Объяснение: