May I ask why you took that decision?

我可否问一下你为什么要作出那样的决定？

《牛津词典》

May I ask a favour of you?

能不能请你帮个忙？

《新英汉大辞典》

May I ask why you are interested in working for us?

我可否问下您为什么有兴趣为我们工作？

youdao

May I ask what you do for a living?

我能问问你做什么工作吗？

在超市遇到的人 - SpeakingMax英语口语达人

This particular website has this free nutrient analysis On the website people may choose to get involved in and there may be charges for those things, I don't really know, but there may be and then they may ask you for identifying information, but it's your option to do that.

网站的营养分析服务,在该网站,人们可以选择使用其他服务,当然,那些可能是收费的,我不是很确定,可能有收费服务,并要求验证个人信息,但这由你自己选择

耶鲁公开课 - 关于食物的心理学、生物学和政治学课程节选

You could say, "May I ask a question?"

你可以说，“我能问你一个问题吗？”

I want to 课堂 - SpeakingMax英语口语达人

May I ask you, Madame Lambert, what it is like to be married to a great magician?

FORBES: Fact and Comment

May I ask you to consider granting my country the honour and also the duty to organise the Games in 2016.

BBC: Juan Antonio Samaranch 'leaves lasting Olympic legacy'

May I ask what the funeral was like this week?

NPR: Celebrating Little Milton's Big Musical Career