是at a ceremony还是on a ceremony,或是两者都可?

是at a ceremony还是on a ceremony,或是两者都可? 词组,是ceremony前加at还是in ,on? Don't stand ______ ,Bill.Just be at home.A on ceremony B in honor C for balance 英语翻译是at a farm 还是on the farm a stormy night前是on还是at on和at区别是in a rainy day 还是 at a rainy day why a cold morning 前介词用什么at还是in说错了，是at还是on Jacques Rogge,___president of IOC,delivered a speech at the opening ceremony of the Beijing Olympic Games on August 8,2008.A.the B./ 是on a party,还是in a party,at a party 为什么? Do you use a computer___work?A at B on C with是A还是C on a winter night.还是 at a winter night? at a snowy night还是on a snowy night be on a meeting还是be at a meeting? can we have a look______your picture?Can we have a look______your picture?A.on B.at C.in D.to 是at 还是on? 这里attended by leader Kim Jong Un 作什么成分?North Korean soldiers relax at the end of an official ceremony attended by leader Kim Jong Un at a stadium in Pyongyang on April 14,2012. a cold morning前的介词用什么如题,是用at还是用on He wore his_____clothes______his birthday.A.best,on B.the best,on C.the best,in D.best,at主要是分不清用on还是at A in a red skirt in the opening ceremony of the Olympic Games,the girl become known to everychineseA=Dressed..是做伴随吗.还是什么?