The four words 对不起 (duìbuqǐ), 请问 (qǐngwèn), 麻烦你 (máfan nǐ) and 劳驾 (láojià) can be a stumbling block for people learning Chinese, as they seem to have similar meanings. All of them might be translated as "sorry" or "excuse me" in various contexts in English.
对不起: "I apologise"
对不起 can be the equivalent of "I'm sorry", "I've let you down", "forgive me" and so on in English, and is used to make apologies. Some examples:
"对不起"相当于英文里的"I'm sorry"、"I've let you down"和"forgive me"等，用于道歉。例子：
duìbùqǐ, wǒ lái wǎnle.
Sorry I'm late.
duìbùqǐ, wǒ bǎ nǐ de huāpíng nòng pòle.
Sorry, I broke your vase.
duìbùqǐ, wǒ méi fǎ bāngzhù nǐ.
I'm sorry, there's no way I can help you.
duìbùqǐ, dōu shì wǒde cuò.
I'm sorry, it's all my fault.
对不起 is not generally used to get someone's attention, preface a request or question, or to ask for someone to repeat something.
For example, you might hear someone say something like:
duìbùqǐ, nǐ kěyǐ bāng wǒ gè máng ma?
Sorry, could you help me with something?
That seems very much like 对不起 is being used to mean "excuse me". But it's probably best to view the above example as someone first apologising for intruding the listener, and then making their request. So 对不起 is still being used as an apology.
These sorts of confusions are unavoidable when learning languages, and you'll rarely find a easy rule that you can memorise. The best thing you can do is focus on input – reading and listening – to try and develop your own feel for the language.
请问: "May I ask?"
The easiest way to understand 请问 is to break it down into the literal meaning of its characters:
请: please, requesting
So literally 请问 is "please can I ask". Thinking of it this way makes its purpose clear: it's for asking questions in a polite way.
因此，"请问"的字面意思是"please can I ask"。以这样的方式去想的话，它的用途就很明显了，它是用于礼貌地询问。
qǐngwèn, yóujú zài nǎlǐ?
Excuse me, where is the post office?
请问 and "excuse me" serve the same function, but they don't actually mean the same thing. Remembering this point will help you to use 请问 correctly.
Because 请问 actually means something like "please can I ask", its uses are much narrower than "excuse me". It always has to come before questions:
由于"请问"实际的意思类似"please can I ask"，因此它的用法比"excuse me"还要狭窄。通常它是放于问题之前：
Have a look at some more examples:
qǐngwèn, zhè li yǒu xǐshǒujiān ma?
Excuse me, is there a toilet here?
qǐngwèn, zhèlǐ kěyǐ shuākǎ ma?
Can I pay by card here?
qǐngwèn, xiānggǎng zhōnglù zěnme zǒu?
Can you tell me the way to Hong Kong Middle Road, please?
Using 请问 is a very nice way of asking questions, especially of strangers, and it can be a good way to get the attention of someone you don't know. In more familiar situations, though, 请问 is usually not necessary. People you know might find it a bit odd if you said 请问 to them.
麻烦你: "Could I trouble you…?"
A very common use of 麻烦你 is to request that someone does something.
麻烦你 + [verb phrase]
By using 麻烦你 you're acknowledging the hassle that you're creating for this person. Let's have a look at some examples:
máfan nǐ kāi gè mén.
Could you open the door for me?
máfan nǐ tì wǒ wènhòu.
Please pass on my regards.
máfan nǐ bāng wǒ kàn kàn zhège.
Could you take a look at this for me, please?
However, 麻烦你 can also precede questions or other statements – it isn't just for requesting. Just remember that whilst 请问 can only come before questions, 麻烦你 can come before questions or instructions, e.g.:
máfan wèn yīxià, běijīng dà jiǔdiàn zěnme zǒu?
Sorry to trouble you – how do I get to the Beijing Hotel?
劳驾: "excuse me", "could I trouble you"
Of the other words listed here, 劳驾 is most similar to 麻烦你.
劳: labour, toil
驾: harness, to drive
麻烦你, 劳驾 can be used to make requests and ask questions.
However, 劳驾 is frequently used to get someone's attention as well as make a request of them.
Have a look at some examples:
láojià, gěi wǒ dào bēi chá.
Excuse me! Could you pour me some tea?
láojià, bǎ zhè shí kuài qián huàn chéng língqián.
Could you change this ten dollar bill, please?
Translated from: chineseboost