该城西门外有一条檀溪河，河宽水急，不易通过。蔡氏兄妹在东、南、北门派重兵把守，只留西门，等待下手。
They sent troops to guard every city gate except the western one ， for outside that gate ， the wide Tanxi River ， with its rapid water ， blocked the road .
檀溪