Learn Hardcore Chinese: bǐrú kǎoshì qián hěnduō xuéshēng dōu hěn jǐnzhāng, bùzhīdào zěnme jiějué wèntí. - For example, before exams many students are very nervous and don’t know how to solve their problems.

很多学生很紧张 is understandable, but sounds a bit less natural and less “group-focused”.
很多学生都很紧张 feels smoother and more idiomatic, and emphasizes that those many students are all nervous.

So 都 here is not about exact number; it’s about distributing the description over the members of the group that has just been mentioned.

Why do we need 很 (hěn) before 紧张 (jǐnzhāng)? Can we just say 学生都紧张?

In modern Mandarin, when an adjective is used as a predicate (A+verb “to be”), 很 often appears before it:

很紧张 – “very nervous / (is) nervous”.

Historically, 很 means “very”, but in sentences like this it can be:

a degree marker (“very nervous”), and / or
a kind of linking word to make the adjective sound like a natural predicate.

If you say 学生都紧张, it’s not wrong, but:

It can sound like a contrast (不紧张 / 紧张 as two opposite categories) or a bit abrupt.
With 很, the sentence sounds more neutral and natural in everyday speech.

So 很多学生都很紧张 is the most natural version in spoken Mandarin.

Why is it 考试前 (kǎoshì qián) and not something like 在考试前 or 考试以前? Are those also correct?

All of these are possible, with small differences in style or emphasis:

考试前 – very common and natural: “before the exam”.
在考试前 – also correct; 在 adds a slight emphasis on time/location (“at the time before the exam”).
考试以前 / 考试之前 – also “before the exam”, slightly more formal or explicit.

In your sentence:

比如考试前很多学生都很紧张…

考试前 is perfectly normal. Adding 在 would not change the meaning much; it’s just slightly more “marked”. For everyday speech and writing, 考试前 is standard.

What is the role of 比如 (bǐrú) at the beginning? How is it different from 比如说 or 例如?

比如 means “for example” or “such as”. At the start of the sentence:

比如考试前 …

it introduces a specific example of a more general situation that has been mentioned (or is understood from context).

Comparisons:

比如 – very common in both speech and writing.
比如说 – slightly more colloquial; literally “for example, say…”. It sounds a bit more like spoken explanation.
例如 – more formal / written; common in essays, reports, exams.

All three can often be swapped without changing the basic meaning, but:

in casual conversation, 比如 or 比如说 is more natural;
in formal writing, 例如 is very common.

Why is it 不知道 (bù zhīdào) and not something like 没知道?

In Mandarin, “不知道” is the natural way to say “don’t know”.

知道 (zhīdào) – “to know”.
Its negative form is 不知道, not 没知道.

The particle 没 is mainly used:

to negate actions or states in the past (没去 = didn’t go),
or to indicate something has not happened yet (还没去 = haven’t gone yet).

“Knowing” here is not a completed past action; it’s a state of not having knowledge, so the standard negative is:

不知道 = “don’t know / not to know”.

没知道 is either wrong or sounds very unnatural in normal Mandarin.

How does 怎么 (zěnme) work in 不知道怎么解决问题? Is that like an embedded question?

Yes. It’s an embedded question (“how to solve the problem”).

Structure:

不知道 – “do not know”
怎么 – “how”
解决问题 – “solve (the) problem(s)”

Together:

不知道怎么解决问题
literally: “(They) don’t know how to solve problems.”

Key points:

怎么 + verb = “how to do [verb]”.
- e.g. 怎么做 (how to do it), 怎么说 (how to say it).
In embedded questions, the word order stays the same as in a normal question, just without a question mark or question particle.
- Question: 怎么解决问题？ – “How do (we) solve the problem?”
- Embedded: 不知道怎么解决问题。 – “(They) don’t know how to solve the problem.”

So yes, it’s an embedded “how” question.

Why is it 解决问题 (jiějué wèntí) and not something like 解决这个问题? Is there a difference?

Both are correct, but they differ in specificity:

解决问题 – “solve problems / solve the problem(s)”.
- More general: could mean “solve problems” in general, or “solve the problem” that is already understood from context.
解决这个问题 – “solve this problem”.
- Points to one specific problem.

In your sentence:

不知道怎么解决问题。

the idea is generally that students don’t know how to handle their problems (e.g. exam stress, questions on the test). Using the bare 问题 keeps it more general and abstract, which is natural here.

Why is there no plural marker like 们 on 学生 or 问题? How do we know they’re plural?

In Chinese, most nouns don’t change form for singular vs plural. Context shows whether something is singular or plural.

很多学生 – “many students”
- The word 很多 (“many”) already tells you it’s plural; 学生 itself doesn’t need to change.
问题 – can mean “question” or “questions”, “problem” or “problems”.
- The context “don’t know how to solve problems” suggests plural.

The plural marker 们 is:

mostly used for people / pronouns (e.g. 我们, 他们, 同学们),
not usually added to objects or abstract nouns like 问题们 (that sounds very odd).

So: no plural ending is needed; it’s inferred from context and words like 很多.

Could we say 很多学生都不知道怎么解决问题 instead? Where does 都 go if we also want to say they don’t know how to solve the problems?

Yes, that’s a very natural variation:

考试前很多学生都不知道怎么解决问题。
“Before an exam, many students all don’t know how to solve the problem(s).”

Word order with 都:

都 usually comes after the subject (or the group you’re talking about) and before the verb:
- 很多学生都不知道…
- Subject = 很多学生
  都 = applies to all those students
  Verb = 不知道

So you can have:

考试前很多学生都很紧张，不知道怎么解决问题。
(focus on them being nervous; then add they don’t know what to do)
考试前很多学生都不知道怎么解决问题。
(focus on them not knowing how to solve the problems)

Can 紧张 (jǐnzhāng) mean more than just “nervous”? I’ve seen it used for “intense” or “tight” situations.

Yes, 紧张 has several related meanings:

(Emotionally) nervous, tense
- 考试前很多学生都很紧张。 – “Many students are very nervous before exams.”
- 别紧张。 – “Don’t be nervous.”
(Atmosphere) tense, intense
- 气氛很紧张。 – “The atmosphere is very tense.”
(Resources, time, supply) tight, in short supply
- 时间很紧张。 – “Time is very tight.”
- 经济很紧张。 – “Money is tight / finances are strained.”

In your sentence it clearly has the emotional meaning: students feel nervous and under psychological pressure.

Is there any difference between 怎么解决问题 and 如何解决问题?

They both mean “how to solve the problem(s)”, but differ in formality and style:

怎么解决问题
- More colloquial, very common in speech and casual writing.
- Used in daily conversation: 你知道怎么解决这个问题吗？
如何解决问题
- More formal / written.
- Common in articles, reports, essays: 我们来讨论如何解决这个问题。

In your original sentence, 不知道怎么解决问题 sounds more natural and conversational than 不知道如何解决问题. The latter would be fine in a more formal text.

Can the time phrase 考试前 move? For example, is 很多学生考试前都很紧张 correct?

Yes, the time phrase 考试前 can move, but some positions sound more natural than others.

Most common patterns:

[Time] + [Subject] + [都] + [Predicate]
- 考试前很多学生都很紧张。
  Very natural.
[Subject] + [Time] + [都] + [Predicate]
- 很多学生考试前都很紧张。
  Also grammatical and understandable, but slightly less smooth than #1. Native speakers often prefer to put shorter time phrases early.
Less natural:
- 很多学生都考试前很紧张。 – This sounds awkward; 考试前 sits in a strange place.

Safest and most natural: put 考试前 near the beginning of the clause, before the subject or right after it, but before 都 and the main predicate.

How are the tones actually pronounced in parts like 很紧张 and 比如? Is there any tone sandhi I should know?

There is some tone sandhi (tone change) to be aware of:

很紧张 (hěn jǐnzhāng)
- Underlying tones: 很 (3), 紧 (3), 张 (1).
- Rule: When two 3rd tones are together, the first one becomes 2nd tone.
- So it’s pronounced: hén jǐnzhāng (2–3–1), not hěn jǐnzhāng.
比如 (bǐrú)
- Underlying tones: 比 (3), 如 (2).
- 3rd tone before a non-3rd tone stays 3rd in standard description, but in natural speech:
  - the first 3rd is often realized as a low or half-3rd before another tone.
- You’ll usually hear something like a shorter, lighter 3rd tone on 比, then a clear 2nd tone on 如.

For practical purposes:

Remember the dictionary tones,
But when speaking, apply the standard 3rd–3rd → 2nd–3rd rule (as in 很紧张),
And listen closely to native speech to mimic the subtle changes.