zhè piān wénzhāng hěn duǎn, wǒ yíhuìr jiù kànwán le.

Because 篇 is the correct measure word for pieces of writing such as articles, essays, and papers.

So the structure is:

• 这 = this
• 篇 = measure word for written pieces
• 文章 = article/text

Together, 这篇文章 means this article.

Using 个 is usually not correct here, because 个 is a general measure word, while 篇 is the natural one for 文章.

篇 is a measure word (also called a classifier). In Chinese, when you point to or count a noun, you often need a measure word between the number/demonstrative and the noun.

Pattern:

• 这 + measure word + noun
• 一 + measure word + noun

Examples:

• 这篇文章 = this article
• 一篇文章 = one article
• 两篇文章 = two articles

For written works, 篇 is very common.

Not necessarily. In Chinese, when an adjective like 短 is used as the predicate, 很 is often added even when the meaning is just is short.

So:

• 文章很短 often means simply the article is short
• it does not always mean very short

This is different from English. In English, very adds strong emphasis. In Chinese, 很 can sometimes just make the sentence sound natural.

If you really want to emphasize very short, context or stronger words can make that clearer.

In Chinese, many adjectives behave like stative verbs. That means they can function directly as the predicate of a sentence without needing a word like is.

So:

• 文章很短 literally looks like article very short but naturally means the article is short

Chinese does not need a separate verb like to be in this kind of sentence.

Here 一会儿 means in a little while or soon.

In this sentence, it suggests that the speaker will finish reading after only a short amount of time because the article is short.

Common meanings of 一会儿 include:

• in a moment / soon
• for a little while
• sometimes a short time

The exact meaning depends on context. Here, because it comes before 就看完了, it means something like it will only take a short while.

This is due to tone sandhi.

Normally, 一 is first tone: yī. But its pronunciation changes depending on what follows.

Before a fourth-tone syllable, 一 usually becomes second tone:

• 一会儿
• 会 is fourth tone
• so 一 becomes yí
• pronunciation: yíhuìr

This is very common in spoken Mandarin.

That 儿 is called erhua. It is an -r ending added to some words, especially in northern Mandarin and standard spoken Mandarin.

So:

• 一会 and 一会儿 are related
• 一会儿 is the more common spoken form

The 儿 often does not carry a full separate syllable in fast speech. It mainly adds an r-colored ending.

Learners do not need to overdo it, but you should recognize it when listening.

就 often indicates that something happens early, quickly, easily, or sooner than expected.

In this sentence:

• 我一会儿就看完了

the 就 suggests:

• it will not take long
• I’ll finish reading it soon
• the action happens quickly

So 就 adds the feeling of before long or in no time.

Without 就, the sentence would still make sense, but it would lose some of that sense of quickness.

看完 is a verb + result complement structure:

• 看 = read/look at
• 完 = finish, be completed

Together, 看完 means finish reading.

This pattern is very common in Chinese:

• 吃完 = finish eating
• 写完 = finish writing
• 做完 = finish doing
• 用完 = finish using up

So 看完了 means the reading is completed.

Because 看完 emphasizes that the article is read all the way through to the end.

Compare:

• 看了 = read / looked at it
• 看完了 = finished reading it

So 完 is important here because the speaker is talking about completing the whole article, not just reading some of it.

Here 了 marks completion or a new situation/result.

Since 看完 already means finish reading, adding 了 makes the completion more explicit and natural in context.

So 看完了 gives the feeling:

• the action will be completed
• the result is reached

In this sentence, it works well because the speaker is saying that after a short while, the result finished reading will happen.

It is related, but learners often find 了 tricky because it can serve different functions.

In 看完了, many teachers analyze 了 as an aspect particle marking completion of the action. In real sentences, though, the line between completed action and new situation is not always perfectly sharp.

What matters most here is:

• 看完 = finish reading
• 了 = the completion/result is now established

So for a learner, the practical understanding is: I’ll have finished reading it.

Chinese time expressions usually come before the main verb.

So the structure is:

• 我 = I
• 一会儿 = in a little while / after a short time
• 就 = then / soon / quickly
• 看完了 = finish reading

A rough pattern is:

subject + time expression + adverb + verb phrase

This is why the time phrase comes before 看完了.

Yes, that is also natural, but the nuance is a little different.

• 我一会儿就看完了 = I’ll finish reading it in a little while / it’ll only take me a short time
• 我很快就看完了 = I’ll finish reading it quickly / very soon

Both are fine. 一会儿 focuses more on a short amount of time, while 很快 directly emphasizes quickness.

Not necessarily. It mainly says the article is short, so the speaker expects to finish it soon.

That may indirectly suggest it will not take much time, but it does not automatically mean:

• the vocabulary is easy
• the content is simple
• the article is easy to understand

The sentence is about length, not necessarily difficulty.

Yes. 一会儿 is flexible and can have different meanings depending on context.

For example:

• 你等我一会儿。 = Wait for me a little while.
• 我一会儿去。 = I’ll go in a little while.
• 他一会儿笑，一会儿哭。 = He laughs one moment and cries the next.

In your sentence, it clearly means after a short time / in a little while, because it is connected to 就看完了.