nǐ wèishénme yíhuìr dāzhàngpeng, yíhuìr shōuzhàngpeng?

Here, 一会儿...一会儿... is a paired pattern meaning one moment... the next..., now... now..., or back and forth between two actions.

So this sentence is not talking about the future time in a little while. It is describing an alternating situation:

• 一会儿搭帐篷，一会儿收帐篷
• one moment you’re putting up the tent, the next you’re taking it down

A single 一会儿 can mean a little while / in a moment, but when it appears twice in this pattern, it usually shows switching between actions or states.

This is because of a very common tone change rule for 一.

Normally, 一 is first tone: yī.
But before a fourth-tone syllable, it changes to second tone: yí.

Since 会 is fourth tone (huì), 一会儿 is pronounced:

• yíhuìr

This is standard Mandarin tone sandhi.

A quick summary:

• yī when said alone or in certain careful contexts
• yí before a fourth tone
• yì before most other tones

The 儿 is part of an erhua ending, a common feature in standard/northern Mandarin pronunciation.

So 一会儿 is pronounced roughly as one word:

• yíhuìr

The 儿 here does not have a separate meaning like child. It is just part of the pronunciation and form of this word.

For learners, the important point is:

• 一会儿 = a fixed word/expression
• do not try to translate 儿 separately here

In some accents, especially outside northern Mandarin, the -r sound may be weaker or absent in actual speech, but 一会儿 is still the standard written form.

Chinese question words usually stay in the same position where the answer would go. They do not move to the front the way English why does.

Compare:

• Statement: 你一会儿搭帐篷，一会儿收帐篷。
• Question: 你为什么一会儿搭帐篷，一会儿收帐篷？

So 为什么 goes where the reason/explanation part belongs, before the action being questioned.

Chinese does not need English-style inversion like:

• Why do you...
• Why are you...

That is an English grammar pattern, not a Chinese one.

Chinese does not use helper verbs the same way English does.

In English, you might naturally say:

• Why are you putting up the tent and then taking it down?
• Why do you keep putting up the tent and taking it down?

Chinese often expresses that idea without extra words like do, are, or keep. The meaning comes from:

• the sentence pattern
• the context
• the repeated 一会儿...一会儿...

That repeated pattern already tells us the action is alternating or repeating, so Chinese does not need a separate word for keep.

Because the sentence is not focusing on the completion of those actions. It is focusing on the back-and-forth alternation.

Bare verbs work well here:

• 一会儿搭帐篷，一会儿收帐篷

This feels like:

• putting it up, then taking it down
• switching between the two

If you added 了, the sentence would sound more like talking about completed events:

• 搭了帐篷，收了帐篷

That shifts the focus toward finished actions, not the confusing repeated behavior the speaker is reacting to.

搭帐篷 means to put up a tent or to pitch a tent.

Here:

• 搭 = to set up / put up / build in a practical sense
• 帐篷 = tent

So 搭帐篷 is a very natural verb-object combination for tents.

Do not interpret 搭 too narrowly as only build. In different contexts, 搭 can mean things like:

• to put up
• to set up
• to construct
• to搭配 or match, in other contexts

But with 帐篷, the meaning is specifically pitch/set up a tent.

No. Here 收 means put away, pack up, or take in.

So 收帐篷 means:

• to pack up the tent
• to take down the tent

This is a very common use of 收 in Chinese. It often means to gather something up and put it away after use.

For example, 收 can also be used in expressions like:

• 收衣服 = take in the clothes
• 收行李 = pack up luggage

A useful nuance:

• 收帐篷 emphasizes putting the tent away
• 拆帐篷 would emphasize dismantling the tent structure

In many everyday situations, English take down the tent could correspond to 收帐篷.

Chinese often links related actions by simply placing them side by side, especially in parallel patterns like this one.

So this is perfectly natural:

• 一会儿搭帐篷，一会儿收帐篷

The repeated 一会儿 already shows the relationship between the two actions, so no extra conjunction is necessary.

English usually needs something like:

• and
• then
• one moment... the next...

Chinese often does not.

The comma helps separate the two matching parts and makes the pattern easy to read.

It often sounds puzzled, impatient, or mildly critical, depending on tone of voice.

Because the speaker is asking why someone is doing something contradictory or pointless:

• one moment setting up the tent
• the next moment taking it down

it can sound like:

• Why are you doing that back and forth?
• Why do you keep changing your mind?

So even though 为什么 is just why, this whole sentence often carries a feeling of confusion or complaint.

With a softer tone, it can still be genuine curiosity.
With a sharper tone, it can sound like criticism.

Yes, if the context is clear, Chinese can omit the subject:

• 为什么一会儿搭帐篷，一会儿收帐篷？

That can still mean Why are you putting up the tent one moment and taking it down the next?

However, keeping 你 makes it more direct and explicitly addresses the other person. It can also make the question sound a bit more pointed.

So:

• 你为什么...？ = more direct, clearly aimed at you
• 为什么...？ = more context-dependent, sometimes slightly less explicit