为什么是in fact而不是in facts

为什么是in fact而不是in facts It is comfortable to__.为什么是sit in而不是be sat in全文是：The chaier looks hard ,but in fact It is comfortable to__. it’s a fact that _______ people had to leave their hometown during the War on Iraq此句中为什么是 on Irag 而不是 in Irag? Considering the fact that he is in poor health,the company let him retired ahead.这里为什么是retired而不是retire? 为什么是Travel in space 而不是Travel in the space in fact 为什么是in the basketball court而不是 on? 为什么是on Friday afternoon而不是in the Friday afternoon 短语be interested in 为什么是be interested in而不是interested in为什么要加be Who打头的特殊疑问句为什么是Who lives in Sanghai.而不是Who live in Sanghai. 英语用法为什么是in high spirits而不是in high spirit now he works in the factory___his father used to work为什么是 where而不是in which 中国制造 为什么是made in china 而不是make in china啊?如题? Everyone in my class _________（be)running in playground.为什么是is而不是are呢? I followed him here,climbed in,sword in hand.为什么是climbed而不是ing形式? 德语词组etw.in Gang bringen中,为什么是in ,而不是im呀? 为什么是My belief in god而不是I belief in god in fact与 in general