ph.

1. They did it by the back door.
他们靠走后门干的。

1. 通过后门;用不正当的途径：By leaps and bounds 飞跃地 | By the back door 通过后门;用不正当的途径 | By the book 按常规

2. 通过后门;用不正当的途：14.turn one's back on/upon...背弃...,抛弃...;对...不闻不问 | 15. by the back door 通过后门;用不正当的途 | 16. bring home the bacon 养家糊口;成功,取胜