Feel free to ask questions if you don't understand.

你要是不懂，可以随便提问。

《牛津词典》

And if you don't understand anything, then there's an active and large community available to ask questions on the mailing list.

而且要是你有什么不知道的，还有活跃的大型社区可以让你在邮件列表中进行提问。

youdao

You cannot fix what you don't understand, so be sure to ask the customer enough questions to learn what is bothering them.

如果你不能理解的话，你就没办法化解，所以要确保你咨询了客户足够的问题，弄清楚了是什么在困扰他们。

youdao

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions any time you don't understand something.

CNN: Shingles

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment anytime you don't understand something.

CNN: Peripheral artery disease (PAD)

In addition to the questions that you've prepared to ask your doctor, don't hesitate to ask questions during your appointment if you don't understand something.

CNN: Occupational asthma