是in1980s还是in the 1980s

是in1980s还是in the 1980s 是in the north还是 in north 是in the USA,还是in USA? 是in UK还是in the UK? 是in Paris 还是in the Paris 是in summer 还是in the summer 是in the university还是in university?是in the college还是in college? 是in the center of 还是in the central of 是in theday还是on the day 是In the internet还是 on? 是at night还是in the night 英语翻译是in the country还是 in country? “在太空中”是in space还是in the space? “在黑暗中”是in darkness还是 in the darkness 问下,住院是in hospital 还是in the hospital 有病住院是in hospital 还是 in the hospital 在火灾中是in fire 还是in the fire 是in western country还是in the western country