búyào shīqù zhège jīhuì.

This is because of tone sandhi with 不.

• 不 is normally fourth tone: bù
• But when 不 comes before another fourth-tone syllable, it changes to second tone: bú

Since 要 yào is fourth tone, 不要 is pronounced búyào.

This pronunciation change is very common:

• 不是 → búshì
• 不要 → búyào
• 不对 → búduì

In writing, it still stays 不, but the pronunciation changes.

Here, 不要 means don’t or must not.

In this sentence, 不要失去这个机会 means something like:

• Don’t lose this opportunity
• Don’t miss this chance

So 不要 + verb is a very common way to make a negative command or strong piece of advice.

Examples:

• 不要说话。 = Don’t talk.
• 不要担心。 = Don’t worry.
• 不要忘记。 = Don’t forget.

They are often similar, and both can mean don’t.

For example:

• 不要失去这个机会。
• 别失去这个机会。

Both are understandable and natural.

A rough difference:

• 别 is often a little more conversational and compact
• 不要 can sound a bit more explicit, firm, or careful

In many everyday situations, either works. A learner should recognize both.

失去 means to lose.

It is often used for losing:

• objects
• abilities
• relationships
• opportunities
• hope, confidence, etc.

So in this sentence, 失去这个机会 literally means to lose this opportunity.

Examples:

• 失去工作 = lose one’s job
• 失去信心 = lose confidence
• 失去朋友 = lose a friend
• 失去机会 = lose an opportunity

In English, we might also say miss the opportunity, but Chinese uses 失去 here.

Chinese word order here is very straightforward:

• 不要 = don’t
• 失去 = lose
• 这个机会 = this opportunity

So the pattern is:

不要 + verb + object

This is a very common structure for negative commands.

Examples:

• 不要吃这个。 = Don’t eat this.
• 不要告诉他。 = Don’t tell him.
• 不要浪费时间。 = Don’t waste time.

So 不要失去这个机会 follows a basic and useful pattern.

这个 means this.

It is made of:

• 这 = this
• 个 = a measure word

So:

• 这个机会 = this opportunity

In Chinese, when you say this/that + noun, you usually need a measure word between them.

Pattern: 这 / 那 + measure word + noun

Examples:

• 这个人 = this person
• 这本书 = this book
• 那个地方 = that place

Since 个 is a very common general measure word, 这个机会 is the normal form.

Because 机会 commonly uses the measure word 个.

So:

• 一个机会 = an opportunity
• 这个机会 = this opportunity
• 那个机会 = that opportunity

Many nouns in Chinese need a measure word when used with numbers or demonstratives like this and that.

For 机会, 个 is the standard and natural classifier.

Yes, and that is a very useful comparison.

• 失去这个机会 = lose this opportunity
• 错过这个机会 = miss this opportunity

Both can work, but they are not exactly identical.

错过 focuses more on missing the right time or letting the chance pass by.

失去 focuses more on losing possession/access to the opportunity.

In many real situations, both are possible:

• 不要错过这个机会。 = Don’t miss this opportunity.
• 不要失去这个机会。 = Don’t lose this opportunity.

The second one can sound a little stronger or more dramatic.

Chinese often leaves out the subject when it is obvious from context.

In English, we usually say:

• Don’t lose this opportunity.

The subject you is understood, even though it is not spoken.

Chinese works the same way here:

• 不要失去这个机会。

The listener understands that the speaker is talking to you, so no subject is needed.

If you wanted to include it, you could say:

• 你不要失去这个机会。

But very often, Chinese leaves 你 out because it is already clear.

It can be any of those depending on tone and context.

不要失去这个机会。 can sound like:

• a command: Don’t lose this chance
• advice: You shouldn’t let this opportunity slip away
• a warning: Be careful not to lose this opportunity

Chinese often relies on context, intonation, and the relationship between speakers to show exactly how strong it is.

So the grammar gives a negative imperative, but the real feeling depends on how it is said.

Because this sentence is telling someone not to do something, not describing a completed event.

了 is often used for:

• completed actions
• new situations
• change of state

But here, the speaker is giving a negative command:

• 不要失去这个机会。 = Don’t lose this opportunity.

Since nothing is being presented as completed, 了 is not needed.

If you added 了, it would change the feeling and would usually not fit this simple command pattern.

Yes.

机会 is commonly translated as:

• chance
• opportunity

Which English word sounds better depends on context.

In this sentence:

• Don’t lose this opportunity
• Don’t miss this chance

Both are good translations.

In general, 机会 often refers to a favorable situation for doing something.

Examples:

• 给我一个机会。 = Give me a chance / opportunity.
• 这是个好机会。 = This is a good opportunity.

It is natural and correct.

It sounds like something you might hear:

• in advice from a friend
• in encouragement
• in advertising or motivational language
• in serious discussion about work, study, or life choices

It is a little more formal or emphatic than some very casual speech, but still completely normal.

A more casual version might be:

• 别错过这个机会。 = Don’t miss this chance.

But 不要失去这个机会。 is absolutely standard Mandarin.