According to Some Aspects of the History of Modern Hindi "Nahîn" "No", "Not" by L. A. Schwarzschild, the Hindi interjection nahîn (and Marathi nahi, Gujerati nahi(m), etc.):
is used as an equivalent of "no" (though it may serve also as a negative adverb), and it represents an enlargement of the old Indo-European negative particile, Sanskrit na.
The question asker's name, Raghav, is of Sanskrit origin, so he and his friend are probably Indian. I've not heard nah used in this way, and it sounds like colloquial Indian English. If so, this nah may be well understood when talking to other Indians but not in other countries. It may be that your friend thinks it is too informal and isn't appropriate to be used in a professional context.
You can ask your friend exactly what he thinks, there may be some acceptable uses. I would advise against using it internationally, because it may be misunderstood.
An answer on Yahoo! Anwsers! explains appending "na" turns a statement into a question, and is Hinglish (or colloquial Hindi English), and can also be used like the English "right?":
Adding na in the ending of any statement makes it a question. eg
Statement: "Tu Calcutta se hai" Question: "Tu Calcutta se hai na ?"
Translation Statement :"You are from Calcutta" Question: "You are from
Calcutta na ?"
I use it many times when I chat Hinglish. But be aware using it
formally since this is informal spoken form and not expected to be
practiced in written form except IM's chats etc.
English equivalent for na would be "right"
Eg " You are from Calcutta right ?"
In the statement "Sorry na" speaker expects the reply or an attention
from you "sorry na"could be explained in many ways.
eg.
- I'm sorry, Is that ok?
- I'm sorry, are you alright now ?
- I'm sorry, Is it fine with you now ?
- I'm sorry, are you happy now ?
According to a blogpost called Indian English – Read it, na! says na finds its way to the end of many Indian English sentences:
Isn’t the genesis or the logic behind Indian English fascinating “na”? Tell me “no”.. My all time favorite is the linguistic interchangeability of no and na and how it discreetly finds its place at the end of each sentence. Did you laugh, na? Amazing, na? I meant our Indian English.
Jason Baldridge wrote in Linguistic and Social Characteristics of Indian English :
When Indians use English, it is often a mixture of English, Hindi, and other languages. B.C., A.S., and S.Singh called this way of speaking kichiri (2.2.3). Kichiri is a meal which is composed of several random ingredients -- a rather accurate description of the way Indians often talk to one another. Even in "pure" Indian English, many Indian terms slip in frequently. Some expressions such as general mai (in general) and ek minute (one minute) are prevalent in Indian English. N.G. mentions the Gujarati expression take care karje (do take care) in 1.1.5. These mixtures come quite naturally when one is acquainted with two or more languages. ... Her use of nahi (no) in 1.1.2, and S.Singh's use of kya (what) in 2.1.1 are typical of the sorts of ways Hindi terms are employed.
...
He says, "Yeah, like this guy Gotham felt like when he went back, no?" This use of no (and the expression isn't it in the same manner) stems from the use of na in Hindi, which is exemplified by N.G. in 1.1.6, "...take care karje appli ker hai na?" This could be roughly translated as "...take care karje can be applied, can't it?"
Some more discussion can be found in Google Books, and here's an example in literature.
The use of "that" in a question isn't right, and "have you" should be reversed.
You'd use "that" if it was a statement, not a question: "it is true that...", for example:
- I would like to tell you that you should have received my gift
- I would like to show you that you must have received my gift
- I would like to inform you that you will soon have received my gift
Your example is a question, so the word needs to match the intention of the question - indicating that this question seeks a yes or no answer:
- I would like to ask you if you have received my gift?
- I would like to ask you whether you have received my gift?
Replacing this changes the meaning of the question:
- I would like to ask you how you have received my gift?
- I would like to ask you when you have received my gift?
- I would like to ask you why you have received my gift?
- I would like to ask you who has received my gift?
Or maybe you meant more like this:
- I would like to ask you a question: have you received my gift?
- I would like to ask: have you received my gift?
Best Answer
Your friend is misremembering technically correct grammar
in the sense that many foreign ESL tests will require students to learn that English has three forms of conditional phrases:
Essentially they break down into statements about the present or future that are possible but uncertain; statements about the present that aren't thought to be likely; and statements about the past that didn't happen but could have, had things been different.
You'll notice there's nothing unusual about 'would' in the then clauses, which is why @tchrist was defending their existence in the if clauses against the oversimplified ESL test idea that 'would' shouldn't ever appear there.
That said, your example doesn't actually qualify for these ESL forms, because you're not talking about anything that you think is contrary to fact.
...but still completely wrong.
'Would' is technically the past tense of 'will' and was used in conditionals to express the future from the perspective of past events.
But that sense of 'things could have been different' was too useful and eventually broadened to include cases where 'things could be different'.
In other words, 'If you would join me, I would be honored' is fine English. It's understood as someone—perhaps British or perhaps falling over themselves a little to be polite—saying
You're just phrasing something that's perfectly possible in a hypothetical way to share some helpful information but to let the other person know that refusal is still perfectly acceptable. (It might still not be, people being how they are, but at least that's what your perfectly grammatical construction is implying and why people use it.)