Tom hid himself behind the door, _____ he could hear the steps of his mother clearly.[ ]

A. from which

B. from there

C. where

D. from where

纳税人在一个纳税年度的中间开业或者由于合并、关闭等原因，使该纳税年度的实际经营期不足12个月的，应当以其( )为一个纳税年度。

A．6个月

B．换算成全年

C．实际经营期

D．3个月