He was often seen____basketball on the playgroundA play Bis played Cto play Dplaying

每题语法请详细说明 可能答案有错 请指出1.the letter ____ by him hasn't been posted yetA written B was written (why A not B)2.He was often seen___ with the peasants.A working B to be worked(why A not B)3.They are busy ____ for the fin The youngman was seen___(get)on a bus just now A bird was seen___(fly)into the classroom yesterday. A stranger was seen___(rush) into the building this morning He was often heard sing .对么 Betty is often seen___(help)the old man with his housework. Betty is often seen___ (heip) the old man with his housework The boy was seen___(fall) off his bike a moment ago. He was often seen____cards with friends.A.play B.playing He was often seen _________(talk)a walking the streat. Betty is often seen___(help)the old man with his housework.答案为什么是to help啊?helping行不行? John is a famous writer now．But he said he was not a __1__student when he was young．He was often l He often read English under the tree when he was young.改为否定句,怎么改? He often ____ (play) basketball after school when he was a student in the past he was careless,so he often _______(make) mistakes He often ______(thinks of) his parents when he was study in Canada.填一个词. He often ______________ (依靠) his sister when he was in Shanghai. he was not interested in his studies and he often gets into trouble with his teacher