When a thief was caught on the premises of large jewellery store 这里为什么是caught on不是in?

In n_____ a thief（小偷） stealing something in a woman's bag when I was on a bus. I n＿＿＿ a thief stealing something in a woman's bag when I was on a bus . The two policemen went ___the thief when he was trying to escape A、off B、with C、after D、on Is it on the morning of Christmas _ the thief was caught?A when B that C before D as When a thief was caught on the premises of large jewellery store 这里为什么是caught on不是in? When a thief was caught on the premises of large jewellery store 这里为什么是caught on不是in? He was ___ ___ the bus when he saw a thief.他在等车的时候看到一个小偷. yesterday when i was going home ,i was a thief .So i ___ the police at onceA ghonedB ghoned forC talked D asked His anger ( )when he saw the thief.He nearly lost control of himself and hit him.A.set up B.was increasedC.was built upD.built up hearing the door opened ,away___ A fleeing the thief B was fleeing the thief C the thief was fleeinD fled the thief when i was on my way home,i saw a thief steal a purse from a girl_______(secret)用所给单词的正确行使填空 the thief was seen____(break)into the jewellery shop when the witness was walking pass it l saw( )thief on( )way to school and( )thief was stealing a purse 1.When advised dieting,Marsha would say,What's the___in working so hard to lose weight,only to gain it all back again?A.concern B.matter C.effect D.pointD2.He was suddenly___with a strange illness when he was about to finish his work.A.seized B,cau _____ from behind the door.A.did the thief rush out.B.the thief was rushing out C.out rushed the thief D.rushed out the thief _______ her mother _______ she was at home when the thief came in.A Each,and B Neither,or C Neither,nor When I came in,I found a thief _____ under the table.A.hiding B.hid C.hidden D.hideWhen I came in,I found a thief _____ under the table.A.hiding B.hid C.hidden D.hide答案选的是C,但是为什么不能选A啊,I found a thief (who was) hiding under the man didn't know__the thief broke into the house and stole all his valuable things.A.it was when that B.when it was that C.that it was when D.was it when that选哪个,为什么?请各位老师赐教.