take the pledge的意思是“发誓要戒酒(to promise to abstain from drinking alcohol)”。 

例句：
I'm not ready to take the pledge yet, but I will cut down.

我还没准备好完全戒酒，不过我会少喝的。

My aunt tried to get me to take the pledge.

我的阿姨设法要我戒酒。