Nhờ tình nguyện viên mà chuồng động vật sạch.

Nhờ ... mà ... is a very common Vietnamese pattern meaning thanks to ... , ... or because of ... , ... with a positive or helpful result.

So in this sentence:

• Nhờ tình nguyện viên = thanks to the volunteer(s)
• mà chuồng động vật sạch = the animal enclosure/cage is clean

This structure often presents:

• a helpful cause first
• then the good result after mà

A very literal breakdown is something like:

• Nhờ X mà Y = Thanks to X, Y happens/is the case

Here, mà helps connect the cause and the result in the pattern nhờ ... mà ....

It does not translate neatly as one single English word. In this sentence, it is part of the fixed structure:

• Nhờ tình nguyện viên mà chuồng động vật sạch.

You can think of it as a connector similar to:

• so
• that
• or simply part of thanks to ... , ...

In natural English, we usually would not translate mà separately.

This pattern is very common:

• Nhờ bạn mà tôi hiểu bài.
  = Thanks to you, I understand the lesson.

So yes, mà is important here because it helps mark the result clause.

Yes. Nhờ has more than one use in Vietnamese.

1. In this sentence

It means thanks to or due to the help of:

• Nhờ tình nguyện viên mà...
  = Thanks to the volunteers...

2. In other sentences

Nhờ can also mean to ask someone for help or to rely on someone to do something:

• Tôi nhờ bạn mở cửa.
  = I ask you to open the door for me.

So the meaning depends on the structure:

• Nhờ + person + mà + result → thanks to
• Nhờ + person + verb → ask someone to do something

That is a very common source of confusion for learners.

Usually, yes. Nhờ normally suggests a good, helpful, or fortunate cause.

So:

• Nhờ tình nguyện viên mà chuồng động vật sạch.
  sounds natural because the result is positive.

If the result is negative, Vietnamese more often uses:

• vì
• do
• tại

For example:

• Vì mưa nên trận đấu bị hoãn.
  = Because of rain, the match was postponed.

Using nhờ with a negative result would usually sound odd, sarcastic, or ironic.

Vietnamese often does not use a separate verb like is/are before adjectives.

In English, we say:

• The animal enclosure is clean.

In Vietnamese, the adjective can act like the predicate by itself:

• Chuồng động vật sạch.

So:

• sạch = clean
• but in the sentence it functions like is clean

This is very normal in Vietnamese:

• Trời nóng. = The weather is hot.
• Nhà lớn. = The house is big.
• Phòng sạch. = The room is clean.

So there is no missing word here. The sentence is grammatically complete.

Chuồng động vật means something like:

• animal cage
• animal pen
• animal enclosure
• animal stall

The exact English translation depends on context.

Breakdown:

• chuồng = a pen, cage, coop, stall, or enclosure for animals
• động vật = animals

So literally it is animal enclosure or animals’ pen/cage.

Depending on the setting, it could refer to:

• a zoo enclosure
• a farm pen
• a shelter cage

English chooses different words depending on the animal and situation, but Vietnamese chuồng is broader.

Vietnamese noun phrases usually put the main noun first and the describing word after it.

So:

• chuồng = the main noun
• động vật = tells you what kind of enclosure it is

That gives:

• chuồng động vật = animal enclosure

This is different from English, where the modifier often comes first:

• animal enclosure

You can think of Vietnamese as often working like:

• noun + modifier

More examples:

• nhà bếp = kitchen
  literally house kitchen
• xe đạp = bicycle
  literally vehicle pedal
• trường học = school
  literally place/school learning

So chuồng động vật follows normal Vietnamese word order.

By itself, tình nguyện viên can mean either:

• a volunteer
• volunteers

Vietnamese nouns usually do not have a built-in singular/plural distinction the way English does.

So the exact number depends on context.

If the speaker wants to make plural very clear, they might say:

• các tình nguyện viên = the volunteers / volunteers

If they want to make singular very clear, they might say:

• một tình nguyện viên = one volunteer

So in your sentence, tình nguyện viên is naturally understood from context as the volunteer(s).

Vietnamese does not use articles the same way English does.

English requires choices like:

• a volunteer
• the volunteer
• the volunteers
• an animal enclosure
• the animal enclosure

Vietnamese often leaves those ideas unspoken unless they are important.

So:

• tình nguyện viên could be a volunteer, the volunteer, or volunteers
• chuồng động vật could be an animal enclosure, the animal enclosure, or animal cages/enclosures, depending on context

If needed, Vietnamese can add words to be more specific:

• một tình nguyện viên = one/a volunteer
• các tình nguyện viên = the volunteers / volunteers
• chuồng động vật đó = that animal enclosure
• một cái chuồng động vật = an animal enclosure

But in many everyday sentences, Vietnamese simply leaves that information out.

Sometimes yes, but nhờ ... mà ... is the standard and most natural full pattern.

With mà:

• Nhờ tình nguyện viên mà chuồng động vật sạch.

Without mà:

• Nhờ tình nguyện viên, chuồng động vật sạch.

The second version may still be understood, but it sounds more like a shortened version. For learners, it is safest to learn and use the full pattern:

• Nhờ X mà Y

That will sound clear and natural.

Yes. Vietnamese often allows you to change the emphasis.

For example:

• Chuồng động vật sạch là nhờ tình nguyện viên.
  = The animal enclosure is clean thanks to the volunteers.

This version puts the result first and then explains the cause.

You could also make the plural more explicit:

• Nhờ các tình nguyện viên mà chuồng động vật sạch.

Or use a slightly different noun:

• Nhờ các tình nguyện viên mà chuồng thú sạch.
  (thú often means animals/beasts, and in some contexts can sound more natural for zoo animals.)

So your original sentence is fine, but it is not the only possible phrasing.

It is basically an adjective meaning clean, but in Vietnamese adjectives can function as the main predicate of a sentence.

So in:

• chuồng động vật sạch

sạch is an adjective, but the whole phrase means:

• the animal enclosure is clean

Learners sometimes call this a stative verb use, because it behaves like the main verb of the sentence.

This happens very often in Vietnamese:

• Cô ấy đẹp. = She is beautiful.
• Món này ngon. = This dish is delicious.
• Phòng sáng. = The room is bright.

So sạch keeps its adjective meaning, but grammatically it can stand where English uses is clean.

Yes, it is understandable and natural enough, especially in simple written or learner-style Vietnamese.

That said, depending on context, a native speaker might choose slightly different wording, such as:

• Nhờ các tình nguyện viên mà chuồng động vật rất sạch.
• Nhờ các tình nguyện viên mà chuồng thú sạch sẽ.
• Chuồng động vật sạch là nhờ các tình nguyện viên.

A few small points:

• các can make the plural clearer
• rất can add emphasis: very clean
• sạch sẽ is a common fuller form meaning clean and tidy

But your sentence is perfectly valid.

A helpful way to parse it is:

• Nhờ tình nguyện viên = cause
• mà = connector
• chuồng động vật sạch = result

So the pattern is:

• [helpful cause] + mà + [result]

In this sentence:

• helpful cause: the volunteer(s)
• result: the animal enclosure is clean

If you remember Nhờ X mà Y, you will be able to understand many similar sentences quickly.