she is senior to me by tow years这句中 by是怎么回事

she is senior to me by tow years这句中 by是怎么回事 英语翻译1,Though Lucy is four years senior to me,she looks young He is senior to me------two years.=He is two years senior--- She is my junior by seven years. He is junior to me by two years.他比我小两岁,在这里为什么用by,不用别的介词? She is 73 years his senior. My elder brother is _____ me by two years . she is older than __ two years A.me for B.I for C.I am by D. she pretended not to see me when I passed by. She asked me,"Do you want to send it by airmail or by ordina bank going car by to is she the Is she going to Hong Kong by plane?