zhè shì chuángdān.

• 这 is the subject and means this.
• 是 is the linking verb, similar to is in English.
• 床单 is the noun that names what the thing is.

So the basic pattern is A 是 B = A is B.

这 can stand on its own as the pronoun this.

In this sentence, 这 is the whole subject: This is a bedsheet.

这个 often means this one or this thing, and it can also be part of a noun phrase. So:

• 这是床单。 = This is a bedsheet.
• 这个是床单。 = This one is the bedsheet / This one is a bedsheet.

The second version is possible, but it usually sounds more contrastive, as if you are distinguishing one thing from another.

Here, 是 links the subject to a noun and identifies it.

So in 这是床单, 是 means something like is in This is a bedsheet.

But it is not exactly the same as English to be in every situation:

• Chinese uses 是 mainly to connect nouns or pronouns:

  • 这是床单。
  • 他是老师。

• Chinese usually does not use 是 before ordinary adjectives:

  • 床单很干净。 = The bedsheet is clean.
  • not 床单是干净

Also, 是 does not change form:

• I am / you are / he is all use 是 in Chinese when appropriate.

Mandarin usually does not have articles like a, an, or the.

So 床单 by itself can mean:

• a bedsheet
• the bedsheet
• bedsheet as a category

The exact meaning depends on context. English has to choose an article, but Chinese often leaves that unstated.

Yes. 这是一条床单 is also correct.

Here, 一条 means one + measure word. For 床单, a common measure word is 条.

So:

• 这是床单。 = natural when you are simply identifying what something is
• 这是一条床单。 = natural when you want to say this is a bedsheet / one bedsheet a bit more explicitly

Both are fine, but the version without the measure word is very common in simple identification sentences.

For this sentence, yes, it is very similar.

English:

• This is a bedsheet.

Chinese:

• 这 是 床单。

So the order is basically:

• subject + linking verb + noun

One important difference is that when this directly modifies a noun, Chinese usually uses a measure word:

• 这条床单 = this bedsheet

So:

• 这是床单。 = This is a bedsheet.
• 这条床单 = this bedsheet

The tones are:

• 这 zhè — 4th tone, falling
• 是 shì — 4th tone, falling
• 床 chuáng — 2nd tone, rising
• 单 dān — 1st tone, high and level

A rough guide:

• zhè sounds like juh with a sharp falling tone, but with the tongue curled back a bit
• shì sounds somewhat like shir without a strong r, also with a falling tone
• chuáng starts with a ch sound made with the tongue curled back, then a rising tone
• dān is a steady high tone

The full rhythm is: zhè shì chuáng dān

That is a common spoken variation.

In careful textbook pronunciation, this character is usually given as zhè. But in everyday speech, many speakers say something closer to zhèi, especially in northern Mandarin and in certain common patterns.

As a learner, zhè is completely safe and standard. If you later notice zhèi in natural speech, that is normal too.

It is one vocabulary word made of two characters:

• 床 = bed
• 单 = sheet/layer in this word

Together, 床单 means bedsheet.

This is very common in Mandarin: many everyday words are made of two characters that work together as one word.

In normal Chinese writing, you usually do not put spaces between words or characters.

So the sentence is normally written as:

这是床单。

Teaching materials often add spaces to help learners see the parts more clearly.

And 。 is the Chinese full stop, the equivalent of an English period .