You've persuaded your father to agree to one of your requests so I should let well alone in case he changes his mind.

你已经说服你父亲答应你的一个要求，因此我不必再插手了，以免使他改变主意。

youdao

Anxiety born in human genes is well enough to give people a hard time, let alone the lifelong anxiety caused by death. It is said that this innate anxiety disorder doesnot only affect humans.

就不用说死亡能让我们一生焦虑了，人类基因中自身携带的焦虑就足以让人们焦头烂额了，这种与生俱来的焦虑症候据说并不是人类的专利。

youdao

I’d like to point out that even science is a science, and still very few people can do it, let alone do it well.

我想指出的是，即使像科学这门学科，也只是为数不多的人才能从事，能做出贡献的就更少了。

youdao

It recognizes that all is not satisfactory, let alone well, in his theater of operations.

CENTERFORSECURITYPOLICY: Two messages for America

More sensibly, they might decide to leave well alone and let the buyer beware.

ECONOMIST: A survey of world trade

All in all, there is no major industrialized economy with universal coverage that has performed as well--let alone better--than the United States in the last decade.

FORBES: Obama's Health Care Reform Tactics