某港口位于东西方向的海岸线上，“远航”号、“海天”号轮船同时离开港口，“远航”号以16海里/小时的速度沿东北方向航行，“海天”号以12海里/小时的速度沿西北方向航行．离开港口一个半小时后两船相距多远？

During the reconstruction of the city, many modern tall buildings went up ______ old shabby houses were torn down.

A．where

B．in what

C．in which

D．which