by the back door

• 通过后门,用不正当的途径

by the back door的用法和样例：

例句

1. The guard opened the gate and Zadak went in.
   那个卫兵打开后门，扎达克走了进去。
2. The locksmith was a handy fellow, and after two hours'work, the door stood open.
   这个锁匠手艺相当高明，两个小时后门就打开了。