They were happy to get the invitation letter...yesterday your fruends went to the cinema,...his collection of students

They were happy to get the invitation letter, weren\'t they? Yesterday your friends went to the cinema, didn\'t they? His collection of stamps was the best, wasn\'t it? The group of students won\'t stay at the hotel, will they? The head teacher didn\'t write the letter, did he? We can arrange a date and time right now, can\'t we?