Learn Hardcore Chinese: tā bù zhīdào zěnmebàn, wǒ jiù gēn tā qù gōngyuán liáotiān. - She doesn’t know what to do, so I went to the park with her to chat.

It links the first clause (the reason/situation) to the second clause (the action taken) and adds a nuance of “so/then, promptly/as a natural response.” It suggests the action was taken readily or decisively.

Can I drop 就, or put it somewhere else?

Dropping it: Grammatical and natural, but you lose the “prompt/so then” feel: 她不知道怎么办，我跟她去公园聊天.
Placement: The most natural spot is after the subject: 我就跟她… You can also reorder other parts (e.g., 我就去公园跟她聊天), but keep 就 before the main verb phrase it modifies.

Why use 跟 (gēn) here? Could I use 和 (hé) instead?

Here 跟 means “with” (accompaniment) and is very common before verbs of movement or interaction: 跟她去, 跟他说.
和 also works (我就和她去…), but 跟 is a bit more colloquial and frequent for “go/do with someone.” In formal writing, 与 is another option.

Does 跟她去 mean “go with her” or “follow her”?

In this structure it means “go with her.” If you wanted “follow,” you’d typically say 跟着她去 (gēnzhe) or 跟在她后面去.

Could I say 陪 (péi) instead of 跟? Any nuance difference?

Yes: 我就陪她去公园聊天. 陪 means “to accompany (to support/keep company),” highlighting a supportive role. 跟 is neutral “with.”

Why no 了 to mark past? Isn’t this about a past event?

Chinese doesn’t require tense marking. Past-ness is clear from context. You can add 了 to emphasize completion or a new situation, but it’s not obligatory.

If I do want 了, where can it go?

Sentence-final 了 for a completed/realized event: 她不知道怎么办，我就跟她去公园聊天了.
After 去 to stress completed motion: 我就跟她去了公园聊天. Both are common; choose based on what you want to emphasize.

Why is it 不知道 and not 没(有)知道?

The negative of 知道 is idiomatically 不知道. 没(有)知道 is generally incorrect in modern Mandarin for “don’t/didn’t know.” To express “didn’t find out/come to know,” use 没(有)弄清楚 / 没(有)得知, etc.

Is 知道 pronounced zhīdào or zhīdao?

In standard modern Mandarin, the second syllable is usually neutral tone: zhīdao. You’ll see zhīdào in some materials, but everyday speech uses the neutral tone.

What exactly does 怎么办 mean? How is it different from 怎么做?

怎么办: “What should (one) do? How to handle/deal with this situation?” It’s about handling a problem.
怎么做: “How to do (it)?” often about procedure/steps for a task. You can also say 该怎么办 to stress “what should be done.”

Is 怎么办 one word?

In characters it’s always two words: 怎么办. In pinyin you typically write it as two words too: zěnme bàn. It’s a set phrase, so it’s often thought of as a chunk.

Why is it 去公园聊天 and not 在公园聊天?

去公园聊天 = go to the park (purpose of motion) to chat.
在公园聊天 = (be) at the park chatting (location of the action). If the going itself matters, use 去; if only the location matters, use 在.

Is 聊天 a separable verb? How do I say “chat for a while”?

Yes, it behaves like a separable verb (verb-object compound).

Short/light action: 聊聊天, 聊聊.
With duration: 聊了会儿天, 聊了很久. All are natural.

Can 聊天 take an object (e.g., “chat about work”)?

Use 聊 + topic for “talk about …”: 聊工作, 聊感情, 聊一聊计划. The set phrase 聊天 itself doesn’t take a topic directly; switch to 聊 + noun/idea.

Any tone sandhi on 不 here? Should it be bú?

No. The rule is: 不 (bù) becomes bú before a 4th-tone syllable. 知 (zhī) is 1st tone, so it stays bù zhīdao. Examples: 不对 → búduì; 不会 → búhuì.

Could I use 所以 or 于是 instead of just a comma?

Yes:

所以 is a neutral “so/therefore”: 她不知道怎么办，所以我就跟她去公园聊天.
于是 is more narrative/sequential “so/thereupon”: 她不知道怎么办，于是我就跟她去公园聊天. Both are fine; 于是 feels a bit more written/narrative.

Do I need 一个 before 公园?

No. Chinese often omits “a/the.” 去公园 can mean “go to a/the park.” Add 一个 only if you need to specify “one (unspecified) park,” which is rarely necessary here.

Could I omit the place and just say “go chat”?

Yes: 她不知道怎么办，我就跟她去聊天. Adding 公园 simply specifies the venue.

What’s the difference between 就 and 才 here? Could I say 才?

就 suggests promptness/earliness or a natural consequence.
才 suggests lateness, difficulty, or “only then.” Replacing 就 with 才 would change the meaning: 我才跟她去公园聊天 implies it happened later than expected or only under certain conditions.