qǐng kàn yǒuxiàoqī.

Here 请 means please. It makes the sentence sound like a polite instruction or request.

So:

• 请看 = please look / please check

Be careful: 请 can also mean to invite or to treat someone in other contexts, but in this sentence it is just the polite please before a verb.

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

In a notice, label, or instruction, 请看有效期 naturally means something like:

• Please check the expiration date
• Please look at the validity period

Adding 你 would usually sound unnecessary here. Short instructions in Chinese are often very compact.

Literally, 看 means to look at or to see, but in many practical situations it can also mean:

• check
• read
• take a look at

So in this sentence, 看 is best understood as check.

For example, on food or medicine packaging, 请看有效期 usually means:

• Please check the expiration date / validity date

有效期 means period of validity, validity period, or in many everyday product contexts, expiration date / valid-until period.

It is made up of:

• 有效 = valid, effective
• 期 = period, term

So the word as a whole refers to the time during which something remains valid or usable.

Common contexts include:

• medicine
• cosmetics
• certificates
• cards or documents
• packaged products

Not always exactly, but it is often translated that way in context.

There are some related Chinese terms:

• 有效期 = validity period / valid-until period
• 到期日 = expiration date / due date / date of expiry
• 保质期 = shelf life / best-before period for products

So:

• for documents, cards, or medicine, 有效期 is very common
• for a single specific date, 到期日 may be more exact
• for food quality, 保质期 is also common

In real-life translation, though, 有效期 is often rendered simply as expiration date if that is the most natural English meaning.

Because 有效期 is a fixed noun compound.

In Chinese, two parts are often joined directly to make one word:

• 有效
  • 期 → 有效期

Using 的 here would sound unnatural. This is similar to how English combines words into set expressions like expiration date or validity period.

So think of 有效期 as one vocabulary item, not a full descriptive phrase.

The structure is:

• 请
  • verb
    • object

So:

• 请 = please
• 看 = check/look at
• 有效期 = validity period / expiration date

This is a normal Chinese word order. The verb comes before what you are looking at.

Compare:

• 请看菜单。 = Please look at the menu.
• 请看说明。 = Please read the instructions.
• 请看有效期。 = Please check the validity period.

Yes, especially in written instructions, notices, labels, or packaging.

It sounds short, direct, and practical. That is normal in Chinese written notices.

In spoken Mandarin, people might say something slightly softer or fuller, such as:

• 请看一下有效期。
• 请先看有效期。
• 麻烦看一下有效期。

So 请看有效期 is natural, but it feels more like a brief written instruction than casual conversation.

一下 often makes an action sound lighter, softer, or more casual.

Compare:

• 请看有效期。 = Please check the validity period.
  
  • brief, direct, notice-like
• 请看一下有效期。 = Please take a quick look at the validity period.
  
  • a bit softer and more conversational

Both are correct. The shorter version is common on signs or packaging because Chinese written instructions often prefer concise wording.

The pinyin is:

• 请 qǐng
• 看 kàn
• 有效期 yǒuxiàoqī

Full sentence:

• qǐng kàn yǒuxiàoqī

Tones:

• qǐng = 3rd tone
• kàn = 4th tone
• yǒu = 3rd tone
• xiào = 4th tone
• qī = 1st tone

A rough rhythm is:

• qǐng KÀN yǒu-XIÀO-qī

Try not to pronounce every syllable equally. 看 and 效 are especially clear and strong here.

Yes. Depending on the situation, you might also see:

• 请查看有效期。 = Please check the validity period.
• 请确认有效期。 = Please confirm the validity period.
• 请核对有效期。 = Please verify the validity period.

But 看 is simple, common, and easy to understand. It is very natural in short practical instructions.

It would commonly appear in situations where someone needs to check whether something is still valid or usable, such as:

• food packaging
• medicine packaging
• cosmetics
• membership cards
• coupons
• certificates
• official documents

So the sentence often functions as a reminder like:

• Please check the expiration/validity information before using it.

That is why it may sound slightly formal or label-like rather than conversational.