Is 用一下 preferable to 用用 or 用一用?

Question

Our Chinese book contains this problem:

I'm interested in the first example.

我不认识这个字，我想用你的词典。
_{Wǒ bù rènshì zhège zì, wǒ xiǎng yòng nǐ de cídiǎn.}

It translates to "I don't recognize this character. I want to use your dictionary." This is rude to say, so we're mean to use one of the structures above to soften it.

So the alternatives are

我不认识这个字，我想用用你的词典。
我不认识这个字，我想用一下你的词典。
我不认识这个字，我想用一用你的词典。

My experience suggests that 用一下 (yòng yīxià) is preferable to 用一用 (yòng yī yòng) or 用用 (yòng yòng). Intuitively, 用用 seems very strange to me. However, the solution given by the teacher was 用用, although the others were considered possible. So I want to clear this up.

Question: Is 用一下 preferable to 用用 or 用一用?

Answer 1

All of them are suitable for the sentence, the difference is very subtle.

“用一下” is kinda formal, you can use this word in almost any occasion, having conversation with your friends, your boss, it's all fine.

"用用" and “用一用” is a little bit casual than "用一下".

But just like I said, the difference is so subtle that most people won't really care about it, especially if you're a foreigner.

Answer 2

Different people may have different opinions. This is more about personal preference other than generic one.

I actually agree with your intuition. I would use 用一下, which sounds more casual to me. This is because 用 sometimes connotes that you use someone as a tool or something, which is not that good, so I'd avoid to use more 用s.

To further soften your tone, you can use the interrogative sentences. Like, 我不认识这个字，我想用一下你的词典, 可以吗？or 我不认识这个字，我能用一下你的词典吗？