While I was at a loss what to do,Mary came to my help.She happened ___some shopping at the same shop.A.to be doing B.doing C.to have done D.to doD为什么不对,能翻译一下意思吗,

i was singing songs 【 】walking home A as B when C at D while I heard someone __ for help while I was reading a novel at homeA cryingB cryC criesD to cry He got excited at the news,while I was calm.为什么用while ,不用when ________?---I was watching TV at home.a. What were you doing when it rained.b. What were you doing while it was raining.c. What did you do while it was raining. While He Yan was at the doctor's.I was going…为什么是doctor's I was having dinner at a restaurant.I see Tony Steele after a while .这里的see为什么是原形?新概念U11摘要写作. i was born in a small mountain town,i moved to the city of Los.mountain town ,the city of while i was ate a meal the telephone is ranging. someone knocked( )the door while i( )my houseworka.at,were doingb.at,was doingc.on,was doingd.on,were doing While it was buying a sounvenir,I called the police是什么意思?while是什么意思? while I am at college. Tom _____(read) a book at 8:00 last night2.While my father _____(watch) the football match on TV,I was listening to music. He got excited at the news,while I was clam.啥意思 He got excited at the news,while I was clam.啥意思 I was (a ) at the bad news At that time I was a 英语xuanzeShe thought i was praising her son,___as a matter of fact , I was scolding him for his bad behavior at school. a while b therefore c which d so that请详细讲原因! About ten years ago when I was a student at college ,I spent my summer holidays working at a museum.(1) was hard for me then,Dad had lost his job and Mum was sick in bed.I was (2) if I would be able to go on with my study the next term.One day while