Learn Hardcore Chinese: rúguǒ nǐ hěn máng, jiù ràng tā lái bāngmáng.

如果…就… means "if…, then…". 就 (jiù) highlights a natural or prompt result/conclusion. You can drop 就: 如果你很忙，让他来帮忙 is still grammatical, just a bit less tight/decisive. Keeping 就 is more idiomatic, especially in careful or written style.

Why is 很 before 忙? Does it really mean "very" here?

With predicate adjectives, Chinese typically uses a degree adverb; 很 (hěn) often functions as a neutral linker rather than strongly meaning "very". 你很忙 is a neutral statement "you’re busy." Bare 你忙 tends to sound contrastive/emphatic. To truly stress degree, use 非常/挺/特别/太…了.

Why isn’t there 是 before 很忙?

Chinese adjectives act as predicates without 是: 你很忙 = "You are busy." 你是很忙 is used only for emphasis/contrast (e.g., "You are indeed very busy (but…)").

What exactly does 让 mean here?

让 (ràng) = "to let/allow" or "to have/tell someone to do something." Pattern: 让 + person + VP. 让他来帮忙 means allow/have him come help. Context decides whether it’s permission ("let") or arrangement ("have/tell").

Can I use 请, 叫, or 使 instead of 让? What’s the difference?

请 (qǐng): polite "invite/ask" → 请他来帮忙 sounds courteous.
叫 (jiào): colloquial "tell/order" → 叫他来帮忙 is common in speech.
让 (ràng): neutral "let/have" (permission or arrangement).
使 (shǐ): formal "cause/make"; not used for asking someone to come help in everyday speech. For superiors, prefer 请 to sound respectful.

Why use 来 before 帮忙? Could I use 去 or omit the direction?

来 (lái) = toward the speaker/reference point: 让他来帮忙 if he comes to where you are.
去 (qù) = away from the speaker: 让他去帮忙 if the help is needed elsewhere.
No direction: 让他帮忙 when movement isn’t the focus. You can also say 让他过来帮忙 to emphasize "come over (to here)."

Is 帮忙 a verb or a noun? How is it different from 帮助?

帮忙 (bāngmáng) is a verb meaning "help (out)" and doesn’t take a direct object: 帮忙做菜 is fine; ✗帮忙我 isn’t.
帮助 (bāngzhù) is verb/noun; as a verb it takes an object (帮助我/他), as a noun (需要你的帮助).

Can I say 帮我忙, 帮我的忙, or 帮我一个忙?

帮我一个忙/帮个忙 = very natural "do me a favor."
帮我忙 = colloquial and common in speech.
帮我的忙 = grammatical but a bit bookish; daily speech prefers 帮我 or 帮我一个忙.

Who does 他 refer to? What about 她?

In speech, 他 (tā) is effectively gender‑neutral ("he/she"). In writing, use 她 for a specific female. For mixed/unknown groups, 他们 is standard.

Can I omit pronouns or other elements if context is clear?

Yes. Chinese allows dropping understood elements. You can say 如果很忙，就让他来帮忙 (omit 你), or simply 让他来帮忙 if the condition is understood.

Where should 就 go? Can I put it after 让 or elsewhere?

Put 就 in the result clause, before the main verb phrase: 如果你很忙，就让他来帮忙. Don’t place it after 让 (✗让就他来…) or right after 如果. You can also say 如果你很忙，那就让他来帮忙 using 那(就).

Can I use 要是 or …的话 instead of 如果?

Yes:

要是你很忙，就让他来帮忙 (colloquial).
你很忙的话，就让他来帮忙 (…的话 attaches to the end of the condition). More formal writing might use 若…便….

Can I add 吧 to make it a suggestion?

Yes. 如果你很忙，就让他来帮忙吧 softens it into a suggestion. Without 吧, it can sound more like a firm instruction.

Do I need 了 anywhere? What would it change?

Not required. A sentence‑final 了 can mark a decision/change of state: 那就让他来帮忙了 ("Alright then, we’ll have him come help"). Avoid inserting 了 inside 让他来帮忙 unless you intend a specific aspectual meaning.

Any tone sandhi to watch for?

你(3)
- 很(3) → the first becomes 2nd tone: ní hěn.
果(3) in 如果 before 你(3) also becomes 2nd in fluent speech: rú guó ní….
帮忙 is bāng (1st) + máng (2nd). General rule: in 3‑3 sequences, the first syllable becomes 2nd tone.

Can I move the conditional to the end?

Prefer it first. Ending with a condition is natural only with …的话: say 你很忙的话，就让他来帮忙, not 就让他来帮忙，你很忙的话 (awkward without reordering).

Is 来帮忙 the only acceptable order? Could I say 帮忙来?

Use 来帮忙, not 帮忙来. Here 来 is the main motion verb ("come (to)"), and 帮忙 is the purpose. With many other verbs, 来/去 can be a directional complement after the verb (e.g., 拿过来), but 帮忙来 is not idiomatic.

Any other natural variations of the sentence?

要是你很忙，那就请他过来帮忙吧。 (more colloquial + polite)
你很忙的话，就让他去帮忙。 (help elsewhere)
如果你很忙，就让他来帮个忙。 (do a favor; softer)

What’s the difference between 就 and 才 in conditionals?

就 signals an expected, immediate, or easy result; 才 suggests the result happens only under stricter conditions or later-than-expected timing. Here the natural choice is 就; using 才 would change the meaning and is unusual for giving a simple suggestion.

Does 忙 need a degree word only in statements? What about questions?

In yes/no questions you can use the A‑not‑A form without 很: 你忙不忙？ In statements, include a degree word (很/挺/非常 etc.) unless you want a marked, contrastive 你忙.