A:that; which
B:/; that
C:/ ; which
D:in which; what
复印纸的型号有A0、A1、A2、A3、A4等,它们有如下的关系:将上一个型号(例如A3)的复印纸在长的方向对折后得到两张下一型号(A4)的复印纸,且各种型号的复印纸的长与宽的比相等,那么这些型号的复印纸的长与宽的比约为( )
Ann is a careful girl.She always checks her exercises to there are no mistakes.