how long ______ this school?

how long ______ this school? 填空:How long has Mr.Black been t_______in this school? ---How long ____you ____(teach) English at this school?---Fo How long （　）you　（ ）in this school How long-this library-? ______is it since you came to this school a,how long b.how o 1.How long has he taught in this school?It's ten years _____ 介词及介词短语--How long have you been in this school?--( )two year how long have you taught in this school?__________(说明理由） A.i how long have you been —— this school?为什么不用On 用in? How ______ ia your home form your school?A.long B.many C.awa how long you this city