If you have any questions at all, please feel free to ask me.

如果你有什么问题，请随意问我好了。

《柯林斯英汉双解大词典》

If you have a problem, ask the invigilator.

有问题就问监考人。

《牛津词典》

If you have any problem, come and ask for help. I will help you to the best of my ability.

如果你遇到任何困难，都来找我吧，我会尽最大的能力帮助你。

youdao

If your friend does not seem to understand how painful your broken heart is, you may ask her to have a heart.

VOA: special.2010.07.18

And if you come and ask a question that you could have easily answered by doing the reading, coming to lecture, or using Google, they're going to have less patience.

所以如果你过来仅仅是问一个,你能很轻松的,通过阅读、上课、或者，在谷歌上搜索就能得到答案的问题，他们会失去耐心的。

麻省理工公开课 - 计算机科学及编程导论课程节选

You could use the "Have you" pattern to ask another friend if they had heard the same rumor.

你可以用“Have you”句型来问你另外一个朋友是否听到了这个传言。

Have you 课堂 - SpeakingMax英语口语达人

If you have to ask, you have obviously never seen one.

WSJ: Tina Gaudoin on Style: Merry and Bright

If you have to ask, you must have spent the last five years with your face buried in a book while the rest of us got on Facebook.

FORBES: How Will Google+, Facebook, LinkedIn, and Twitter Look in One Year?

If you have to ask who that is, get to Googling.

NPR: Report: Iran Halted Nuclear Ambitions