shēngrì de shíhou, fùmǔ sòng gěi tā yí jiàn xiǎo lǐwù, suīrán bú guì, dànshì tā hěn gāoxìng.

生日的时候 means at the time of her birthday or more naturally on her birthday.

Chinese often puts time expressions near the beginning of the sentence to set the scene first. So:

• 生日的时候，父母送给她一件小礼物。
• Literally: At birthday time, her parents gave her a small gift.

You could also say:

• 在生日的时候...
• 过生日的时候...

But 生日的时候 is natural and concise.

的时候 means when, at the time of, or during.

It attaches to a word or phrase to create a time expression:

• 生日的时候 = when it was her birthday / on her birthday
• 小时候 = when one was little / in childhood
• 吃饭的时候 = when eating / during mealtime

In this sentence, it turns 生日 into a time phrase.

Chinese often leaves out possessive words like her when the meaning is obvious from context.

So:

• 生日的时候 can mean at her birthday
• 父母 can mean her parents here

If you wanted to be more explicit, you could say:

• 她生日的时候，她父母送给她一件小礼物。

But that sounds a bit more repetitive. Chinese frequently omits things that are understood.

送给 is a very common pattern meaning to give as a gift to or to present to.

Breakdown:

• 送 = to give, deliver, present
• 给 = to someone / give to

So:

• 送给她一件小礼物 = give her a small gift

You can think of the pattern as:

• 送给 + person + thing

Example:

• 我送给他一本书。
• I gave him a book.

In everyday speech, people also often say:

• 送她一件小礼物

Both are natural.

In this sentence, 给 is part of the verb pattern 送给, not a separate preposition.

So the structure is:

• 父母 送给 她 一件小礼物
• parents gave to her a small gift

Chinese has several ways to express this kind of idea:

1. 送给她一件小礼物
2. 给她送一件小礼物

Both are grammatical, but the sentence you have uses 送给 as a set expression.

件 is a measure word for certain items, especially:

• clothing
• matters/events
• some individual items

In Chinese, when a noun is counted, you usually need a measure word:

• 一件礼物 = one gift
• 一件衣服 = one piece of clothing

For 礼物, people often say both:

• 一件礼物
• 一个礼物

But 一件礼物 sounds a bit more natural when referring to a specific gift item.

In Chinese, adjectives usually come before the noun when directly describing it.

So:

• 小礼物 = small gift
• 大房子 = big house
• 新书 = new book

If you say 礼物小, that becomes more like the gift is small, which is a different structure.

Compare:

• 一件小礼物 = a small gift
• 礼物很小 = the gift is small

This is a tone change rule.

一 is normally first tone: yī. But its pronunciation changes depending on the tone of the next syllable.

Rules:

• before a 4th-tone syllable, 一 becomes yí (2nd tone)
• before other tones, it often becomes yì (4th tone)
• when said alone, it stays yī

Here:

• 件 is jiàn (4th tone)

So:

• 一件 is pronounced yí jiàn

These are two different pronunciation phenomena.

1. 不 changes tone

不 is normally bù (4th tone), but before another 4th-tone syllable, it changes to bú (2nd tone).

Here:

• 贵 = guì (4th tone)

So:

• 不贵 is pronounced bú guì

2. 的 is usually neutral tone

In 的时候, the 的 is grammatical, not stressed, so it is pronounced lightly as de with a neutral tone.

That is very common for 的 in everyday Mandarin.

虽然...但是... means although... yet... / although... but...

It is a very common pattern for contrast.

In this sentence:

• 虽然不贵，但是她很高兴。
• Although it wasn’t expensive, she was very happy.

Structure:

• 虽然 + idea A, 但是 + idea B

Examples:

• 虽然很累，但是我还要工作。
• Although I’m tired, I still need to work.

In conversation, 但是 is sometimes omitted if the contrast is already clear:

• 虽然不贵，她很高兴。

But using both parts is especially good for learners because it makes the structure very clear.

The understood subject is the gift.

Chinese often omits a subject when it is obvious from context. So:

• 虽然不贵
• literally: although not expensive

What is not expensive?

• the small gift that was just mentioned

If you wanted to spell it out, you could say:

• 虽然礼物不贵，但是她很高兴。

But Chinese often prefers the shorter version when the meaning is clear.

Chinese often repeats the subject after a contrast marker like 但是 to make the sentence clear and natural.

So:

• 虽然不贵，但是她很高兴。

The 她 helps show that:

• the gift is the thing that is not expensive
• she is the one who is happy

Without 她, the sentence would be less clear.

Not always. In Chinese, 很 + adjective is often just the normal way to make a statement.

So:

• 她很高兴 usually means she is happy
• not necessarily she is very happy

If you remove 很 and say 她高兴, it can sound incomplete or marked in many contexts.

So 很 here is often more grammatical than strongly emphatic.

If you really want to stress very, you could say:

• 她非常高兴
• 她特别高兴

Yes. Both 高兴 and 开心 can mean happy.

• 高兴 is slightly more neutral and standard
• 开心 can sound a bit more everyday and emotional

So this would also work:

• 虽然不贵，但是她很开心。

Both are natural.

Yes. Both are natural.

Compare:

• 父母送给她一件小礼物
• 父母给她送一件小礼物

Both mean her parents gave her a small gift.

The first one treats 送给 almost like a combined verb. The second one uses 给她 before the verb phrase.

For learners, both are useful to know.

A helpful breakdown is:

• 时间: 生日的时候
• 主语: 父母
• 动词: 送给
• 间接受词: 她
• 直接受词: 一件小礼物
• 转折部分: 虽然不贵，但是她很高兴

So the overall structure is:

• [Time], [subject] [verb] [person] [thing], although [contrast], but [result].

This is a very common Chinese word order pattern:

1. time first
2. main event
3. extra comment or contrast after that

Chinese writing often uses commas to separate natural chunks of information, sometimes more freely than English.

Here the commas help divide the sentence into parts:

• 生日的时候，
• 父母送给她一件小礼物，
• 虽然不贵，
• 但是她很高兴。

They guide the reader through:

1. the time
2. the main action
3. the contrast
4. the result

So the punctuation reflects the sentence’s rhythm and structure.