Hàng xóm của Lan đã cho tôi mượn ô khi trời bắt đầu mưa.

In Vietnamese, possession is often shown with của, which means of.

So:

• hàng xóm = neighbor
• của Lan = of Lan / Lan’s

Together, hàng xóm của Lan literally means the neighbor of Lan, which in natural English becomes Lan’s neighbor.

This structure is very common:

• bạn của tôi = my friend
• nhà của Lan = Lan’s house

In casual speech, Vietnamese sometimes drops của in certain expressions, but with a phrase like this, hàng xóm của Lan is clear and natural.

By itself, hàng xóm can mean neighbor or neighbors, depending on context. Vietnamese nouns usually do not change form for singular vs. plural.

In this sentence, it is understood as singular because the rest of the sentence sounds like one specific person lent the umbrella.

If you wanted to make plurality clearer, Vietnamese could add words like:

• những hàng xóm của Lan = Lan’s neighbors
• một người hàng xóm của Lan = one of Lan’s neighbors / a neighbor of Lan

Đã marks that the action happened in the past or was completed.

So in:

• đã cho tôi mượn ô

the word đã shows that the lending already happened.

Vietnamese does not have verb conjugations like English give/gave/given, so words such as đã, đang, and sẽ help express time:

• đã = past
• đang = ongoing
• sẽ = future

However, đã is not always required if the time is already obvious from context. Vietnamese often relies on context a lot.

This is a very important pattern.

• mượn by itself usually means to borrow
• cho mượn means to lend

So:

• Tôi mượn ô = I borrow an umbrella
• Lan cho tôi mượn ô = Lan lends me an umbrella

In the sentence:

• đã cho tôi mượn ô

the structure is:

• cho = let/give
• tôi = me
• mượn = borrow

Literally, it is something like let me borrow an umbrella, which is how Vietnamese commonly expresses lend me an umbrella.

Because in this pattern, the person receiving the borrowed item comes right after cho.

Structure:

cho + person + mượn + thing

So:

• cho tôi mượn ô = lend me an umbrella
• cho Lan mượn sách = lend Lan a book

This is different from English word order, so it is worth memorizing as a whole pattern.

Vietnamese does not have articles like a, an, and the in the same way English does.

So ô can mean:

• an umbrella
• the umbrella
• umbrella

The exact meaning depends on context.

If Vietnamese wants to be more specific, it can use a classifier or number:

• một cái ô = an umbrella / one umbrella
• cái ô đó = that umbrella

In your sentence, just ô is perfectly natural.

Here, ô means umbrella.

Both ô and dù can mean umbrella in Vietnamese, but usage can vary by region and habit. In many contexts, they are interchangeable.

For example:

• mang ô = carry an umbrella
• mang dù = carry an umbrella

A learner may hear either one in real life.

Khi means when.

It introduces the time clause:

• khi trời bắt đầu mưa = when it started to rain / when the sky started raining

So the sentence tells you when the main action happened.

Vietnamese often places time clauses either after or before the main clause:

• Hàng xóm của Lan đã cho tôi mượn ô khi trời bắt đầu mưa.
• Khi trời bắt đầu mưa, hàng xóm của Lan đã cho tôi mượn ô.

Both are natural.

In weather expressions, trời often appears and refers to the sky, the weather, or just the general outdoor conditions.

So:

• trời mưa = it rains / it is raining
• trời nắng = it is sunny
• trời lạnh = it is cold

In your sentence:

• trời bắt đầu mưa literally means something like the sky/weather started raining
• natural English: it started to rain

This is a very common Vietnamese way to talk about weather.

It can correspond to either in English.

• bắt đầu = begin/start
• mưa = rain

So:

• trời bắt đầu mưa = it began to rain / it started raining

Vietnamese does not need an extra word like English to in began to rain.

The sentence follows a very typical Vietnamese order:

Subject + time/aspect marker + verb phrase + time clause

Breaking it down:

• Hàng xóm của Lan = subject
• đã = past marker
• cho tôi mượn ô = verb phrase
• khi trời bắt đầu mưa = when-clause

So literally:

• Lan’s neighbor + past marker + lent me an umbrella + when it started to rain

Vietnamese word order is often quite straightforward once you recognize the chunks.

Yes, it could, depending on context.

For example:

• Hàng xóm của Lan cho tôi mượn ô khi trời bắt đầu mưa.

This can still be understood, especially if the past time is already clear from the situation or the story.

Adding đã makes the past meaning more explicit. Vietnamese often balances between grammar markers and context, so both versions may appear.

You could say:

• Hàng xóm của Lan đã cho tôi mượn một cái ô khi trời bắt đầu mưa.

Here:

• một = one / a
• cái = classifier for many objects
• ô = umbrella

This is more explicit, but the shorter version without một cái is still very natural.

A natural yes-no question would be:

• Hàng xóm của Lan đã cho tôi mượn ô khi trời bắt đầu mưa phải không?

Adding phải không? is a common way to ask right? / is that correct?

You could also ask about one part of the sentence:

• Ai đã cho tôi mượn ô khi trời bắt đầu mưa? = Who lent me an umbrella when it started to rain?
• Hàng xóm của Lan đã cho tôi mượn gì? = What did Lan’s neighbor lend me?

You usually negate the verb with không:

• Hàng xóm của Lan đã không cho tôi mượn ô khi trời bắt đầu mưa.

This means:

• Lan’s neighbor did not lend me an umbrella when it started to rain.

In everyday speech, people may also say:

• Hàng xóm của Lan không cho tôi mượn ô khi trời bắt đầu mưa.

The exact nuance depends on context, but both are understandable.

No. They are related, but not the same.

• cho by itself often means give
• cho mượn means lend

Compare:

• Lan cho tôi ô. = Lan gives me the umbrella.
• Lan cho tôi mượn ô. = Lan lends me the umbrella.

With cho mượn, the idea is that the item is borrowed and will usually be returned.

Yes, absolutely.

You can say:

• Khi trời bắt đầu mưa, hàng xóm của Lan đã cho tôi mượn ô.

This version emphasizes the timing first. Vietnamese is flexible about placing time expressions and time clauses at the beginning or end, as long as the sentence remains clear.