Being an assistant generally involves asking lots of questions, in fact some days I ask so many questions I begin to wonder whether people think I'm a bit thick.I'm lucky that everyone I deal with regularly understands that questioning is vital if we want to get something right, but how do you handle a boss, co worker or even client that hates being questioned on their instructions?

In the longer term, I think it's important to have a think about why this person responds negatively to being questioned - Are they too busy? Do they understand why you are asking questions (presumably so you can be more helpful to them)? Is this something you should already know? Do they not know the answers - are you even asking the right person? Do you know how this person prefers to communicate (i.e. by email, phone, face to face or even scribbled notes on a post-it) and is that how you are presenting the question to them?

One way of approaching someone who is reluctant to be questioned on their requests is to start with what you do know - paraphrase the instructions as you understand them 'just to be confirm' and then slip in your question. Another method is to propose a course of action you think would be appropriate - you'll soon find out whether that's what they have in mind.

When it comes down to it, you're asking questions to make sure you can do the best job of helping someone, but you can only go on what they'll tell you - most rational people will understand this.

Here's an interesting thought on the difference between questions and questioning from Tammy Lenski:

I think there’s a difference between asking questions and questioning. When I have a questioning attitude, I’m really expressing disbelief, doubt or skepticism about the other person. When I’m asking questions, I’m expressing interest, curiosity, and wanting to learn. 

From: http://conflictzen.lenski.com/questions-are-different-than-questioning/