The acrobatic show will begin at 6 p.m. and continue until audience in

well. I'm giving some other examples to legitimate the answer option 'A'.

Hi AryamaDuttaSaikia,
If I say:
Please write the answer script until you answer the full marks.

Note: I intend to mean that when you answer full marks then you will stop writing. So, here until is correct.

But, if I say:
Please write the answer script as long as you answer the full marks.

Note: Here, My intended meaning is totally different to the first one. Now, you will be astonished that HOW does a student write on the answer script after answering full marks? Ok. I’m telling you the secret matter how does a student write MORE after answering the full marks within a certain time. Suppose you are in exam hall. Your duty is to answer full marks (100 marks) within 2 hours (120 minutes). When it is 90 minutes, you answered all the questions (equivalent to 100 marks). You are still left 30 minutes. WHAT will you do now? Will you go out from the exam hall? I think it will be wrong decision to go out from the exam hall! Here, you should modify, check, re-check and ADD MORE POINT and give example with every NEW point you wrote. Now, your question is HOW will you get the blank space to ADD MORE point in the answer script? Actually, the secret matter is: you put one half (1/2) blank page for every question so that you CAN write SOMETHING MORE if you finish your exam before 120 minutes. But, remember that you’ve finished your exam (writing 100 marks) in 90 minutes. Now, you are still writing for last 30 minutes. So, my question is: WHICH one will you use? UNTIL or AS LONG AS in this regard?

I will ask this question in this forum until I get the solution.. This sentence is perfectly fine-there is no oppose about this sentence.

I will ask this question in this forum as long as I get the solution.
>>This is very bad-we should not ask any question for several times after getting the proper answer. So, this sentence is not legitimate at all. If I am in my target (I'll boil water until rice is cooked-the target is cooking rice), why do I ask any question again and again? I should not do it, isn’t it?

I will ask this question in this forum as long as I get the solution for better understand.
This is legitimate sentence. Here, better understand indicates WHY I ask this question for several time. This indicates the actual reason for asking this question again and again.

In the original question (the acrobatic show…), the questioner did not mention any specific reason WHY the acrobatic show will continue after getting interest. So, I think, ‘until’ is correct in the original question not ‘as long as'.

also, I want to have attention to all the verbal expert of GMAT CLUB. Please, correct me, if I'm wrong.

Option A doesn't sound right. We need an "end point" after until.

The acrobatic show will begin at 6 p.m. and continue until audience interest lasts.
should actually be
The acrobatic show will begin at 6 p.m. and continue until audience interest ends.

But this is just a quick reply until Aryama gets back to you.

Hi AjiteshArun,
I haven't got any response yet. I'm waiting for Jamboree response. Thanks...

I haven't gone through all the other responses, but I'll try to help you out. There are two major points I think we should discuss: (a) the change in meaning and (b) whether some constructions are impossible.

We'll not leave until the police arrive.
and
We'll not leave as long as the police arrive.

The first one gives us something after which we can "leave" (an event or a time). The second one, however, changes the meaning (it becomes a conditional statement). The second basically says that if the police "arrive", we'll not leave.

We'll not leave as long as the police continue locking innocent people up.

This one is possible.

We'll leave as long as the police (also) leave.

In this one the "duration" meaning is not possible (this is actually a condition).

Now for the two sentences you are interested in:
(a) The acrobatic show will begin at 6 p.m. and continue until audience interest lasts.
audience interest lasts doesn't give us an "event" or "particular time". Instead, it gives us a "duration". This construction is not possible. I'm still going by sound on this one though. You're welcome to ask for a second opinion.

(b) Unfortunately, both the sentences are incorrect. Even if we ignore other mistakes, we just can't say

I will ask this question in this forum as long as I get the solution for better understanding.

The problem is that we don't want to ask the question as long as we get a solution. We want to ask the question as long as it remains unanswered (again, we're going for the "duration" meaning, not the conditional statement). A shorter example is:

You won't know until you try.
Once you try, you'll know.

You won't know as long as you try.
If you keep trying, you won't know.

begins is wrong usage as it can be used in simple present tense only
Correct usage is will begin
option C doesn't make much sense
only in option E, modifier error is being taken care of
correct answer - E

AjiteshArun : Great explanation and worthy to learn.
But, Is this question worthy to lose my sleep as I also marked A ?

The probability that you will get a question that tests this is very small, but more generally, you should not worry too much about getting a question wrong, as every mistake is just an opportunity to learn something (and while everyone makes mistakes, not everyone makes an effort to learn from them). So look at it this way: maybe you should feel better now that there is one less (small) thing that you have to worry about on the exam.

Also, this question appears to be based on a very old GMAT question (almost word for word).

The "until" got me. So is it safe to assume that "until" is used when an activity stops immediately and "as long as" is used if the activity is stopping gradually?