Learn Hardcore Chinese: wǒ qù shítáng chīfàn de shíhou, shùnbiàn bāng shìyǒu dài le yì bēi kāfēi. - When I went to the cafeteria to eat, I also brought a cup of coffee for my roommate.

sounds awkward and unnatural. In everyday Chinese, you almost never move ...的时候 to the very end as an afterthought the way you sometimes can in English.

Why do we say 去食堂吃饭, not just 去食堂? Isn’t it obvious that you go to the cafeteria to eat?

Both are possible, with a slight nuance difference:

我去食堂的时候
→ When I went to the cafeteria (reason not stated; could be to eat, to meet someone, to work, etc.).
我去食堂吃饭的时候
→ When I went to the cafeteria to eat (purpose is explicit).

So 吃饭 adds the idea of purpose.

Also, 去 + 地点 + 吃饭 is a very common pattern in Chinese:

去朋友家吃饭 – go to a friend’s place to eat
去饭店吃饭 – go to a restaurant to eat

You could say only 去食堂, but then the purpose is just left to context, not explicitly said.

Why is 吃饭 used instead of just 吃? What does 吃饭 really mean?

吃饭 literally looks like eat rice, but in modern Mandarin it usually means:

to have a meal / to eat (a main meal)

So 去食堂吃饭 is essentially go to the cafeteria to have a meal.

Using only 吃 is possible but feels incomplete unless the object is obvious from context:

我去吃了。 – I’m going to eat (something) / I went to eat (something).

In a neutral standalone sentence, 去吃饭 is more idiomatic than 去吃 because 吃饭 is a fixed, very common verb‑object chunk meaning have a meal.

In 顺便帮室友带了一杯咖啡, what is the difference between 帮, 帮助, and 帮忙? Could I say 帮助室友带了一杯咖啡?

帮 (bāng)
- Basic, everyday verb to help (someone do something).
- Pattern: 帮 + person + verb phrase
  - 帮室友带了一杯咖啡 – helped my roommate by bringing a cup of coffee.
帮助 (bāngzhù)
- Often more formal; can be a verb or noun.
- As a verb it’s usually 帮助 + person (optionally with a phrase indicating in what aspect):
  - 帮助了室友 – helped the roommate
  - 在学习上帮助他 – help him with his studies
- Saying 帮助室友带了一杯咖啡 is grammatically odd: it jams two verbs (帮助 and 带) together in a way native speakers don’t use.
帮忙 (bāngmáng)
- Literally help‑busy, but means to do someone a favor / to lend a hand.
- Patterns:
  - 帮忙带一杯咖啡 – help out by bringing a cup of coffee
  - 帮室友的忙 – help your roommate (noun: their “favor”)

For this sentence, 帮室友带了一杯咖啡 (or with 顺便) is the natural choice. 帮助 doesn’t fit directly before another verb like 带 here.

What nuance does 顺便 add? How is it different from 也 or 还?

顺便 (shùnbiàn) means:

while conveniently doing something else; incidentally; since I was already there

It implies:

The extra action (bringing the coffee) did not require much extra effort.
It was done along the way of the main action (going to eat at the cafeteria).

Compare:

我去食堂吃饭的时候，顺便帮室友带了一杯咖啡。
→ While I was going anyway, I conveniently brought a coffee for my roommate.
我去食堂吃饭的时候，也帮室友带了一杯咖啡。
→ I also helped my roommate by bringing a coffee. (Just adds another action; no “convenience” nuance.)
我去食堂吃饭的时候，还帮室友带了一杯咖啡。
→ I even / in addition helped my roommate bring a coffee. (Can feel like “on top of that”.)

Placement: adverbs like 顺便 usually go before the main verb:

顺便帮我买点儿东西。
去银行的时候顺便取一下钱。

What exactly does 了 do in 带了一杯咖啡? Is it just “past tense”? What changes if we remove it?

了 here is the aspect particle marking completed action (perfective aspect), not a pure past‑tense marker.

带了一杯咖啡
→ The bringing of the coffee is viewed as a completed, specific event.

If you remove 了:

我去食堂吃饭的时候，顺便帮室友带一杯咖啡。

This can sound like:

a plan / instruction / suggestion (e.g. you telling someone what to do), or
a habitual or general statement if the rest of the context supports that.

So:

有了了 → usually a specific past occurrence (here, clearly “I did it”).
没有了 → more neutral in time; needs context to know if it’s future, habitual, or just a bare description.

Chinese does not have obligatory tense like English; aspect and time expressions carry most of that meaning.

Why is there no 给 in 帮室友带了一杯咖啡? Can I say 帮给室友带了一杯咖啡 or 给室友帮带了一杯咖啡?

The basic structure is:

帮 + person + verb phrase

So:

帮室友带了一杯咖啡 = help roommate (by) bringing a cup of coffee.

You cannot insert 给 between 帮 and 室友:

✗ 帮给室友带了一杯咖啡 – incorrect
✗ 给室友帮带了一杯咖啡 – very unnatural

But you can form a different, also natural pattern without 帮:

顺便给室友带了一杯咖啡。
→ conveniently brought a cup of coffee for my roommate.

Here the pattern is:

给 + person + 带 + object – bring something for someone.

So:

帮室友带 – emphasize “helping” the roommate.
给室友带 – emphasize “bringing it for” the roommate.

You usually choose one of these patterns, not mix 帮 and 给 right next to each other.

Why is 带 used for the coffee? Could we use 拿 or 买 instead? What’s the difference?

Common verbs here:

带 (dài) – to take/bring (something) along with you from one place to another.
- 帮室友带了一杯咖啡 suggests you carried the coffee from the cafeteria back to where your roommate is.
拿 (ná) – to take / to hold / to pick up something, focusing more on the act of taking or holding it, not necessarily from place A to B for someone else.
- 帮室友拿了一杯咖啡 is possible if you are in the same place and you pick up or hold the coffee for them, but for “bring back a cup of coffee from the cafeteria” 带 is more natural.
买 (mǎi) – to buy.
- 帮室友买了一杯咖啡 emphasises purchasing the coffee for your roommate. It does not explicitly say you brought it to them, though that is usually implied in context.
- You can actually combine ideas in a longer sentence, for example:
  - 我在食堂帮室友买了一杯咖啡，又帮他带回寝室。

In the original sentence, the important idea is that you brought a coffee along with you while you were already going, so 带 fits very well.

Why is 杯 used with 咖啡? Is 一杯咖啡 like “one coffee”? Could we say 一个咖啡?

Chinese uses measure words (classifiers) between numbers and nouns.

For drinks in cups or glasses, 杯 (cup, glass) is a very common measure word:

一杯咖啡 – one cup of coffee
两杯茶 – two cups of tea
一大杯可乐 – one large cup of cola

You cannot say:

✗ 一个咖啡 – ungrammatical in standard Mandarin.

If you want to talk about the physical cup as an object, you use 杯子:

一个杯子 – one cup (the container itself)

But when you are ordering or mentioning a drink amount, you normally say 一杯咖啡, not 一个咖啡.

(Pronunciation note: 一杯 is usually pronounced yì bēi, but in ordinary speech the 一 often surfaces as yí before a fourth‑tone syllable: yí bēi kāfēi.)

How is 时候 pronounced, and how is it different from 时? Could I say 我去食堂吃饭时 instead?

Pronunciation:

Characters: 时 (shí, 2nd tone)
- 候 (hòu, 4th tone)
But in the word 时候, the second syllable is usually neutral tone: shíhou.

Meaning:

时候 means time / moment / when, used very broadly in everyday speech.

Difference from 时:

时 is more formal / literary and appears in many set words:
- 平时 – usually, at ordinary times
- 小时候 – when I was little (literally: small‑time)
- 吃饭时 – when eating

Yes, you can say:

我去食堂吃饭时，顺便帮室友带了一杯咖啡。

This sounds a bit more written/formal than ...的时候 but is correct and natural.

Where exactly does 顺便 go in the sentence? Could I say 我顺便去食堂吃饭的时候帮室友带了一杯咖啡?

Typical, clear structure of the original:

我 (subject)
去食堂吃饭的时候 (time clause)
，顺便 (adverb)
帮室友带了一杯咖啡 (main action)

So the standard pattern is:

[Subject] + [time phrase] + [adverb] + [verb + objects]

You can also front the time phrase:

去食堂吃饭的时候，我顺便帮室友带了一杯咖啡。

Placing 顺便 inside the time clause, like:

✗ 我顺便去食堂吃饭的时候帮室友带了一杯咖啡

is confusing or unnatural, because it makes 顺便 look like it modifies 去食堂吃饭, not 帮室友带. The listener struggles to parse what is “convenient” relative to what.

So keep 顺便 right before the main verb of the extra action (here 帮):

...，顺便帮室友带了一杯咖啡。

The Chinese sentence clearly refers to a past event. But apart from 了, there’s no past tense. How does Chinese express tense here? How would I say it for the future or as a habit?

In this sentence, “pastness” is conveyed by:

Context (we’re describing something that happened), plus
了 after 带, marking completed action.

Chinese does not have verb endings for past / present / future like English. Instead it relies on:

Time expressions (昨天, 刚才, 明天, 以后 etc.)
Aspect particles (了, 着, 过)
Context.

Changing the sentence:

Future / plan:
- 我去食堂吃饭的时候，会顺便帮室友带一杯咖啡。
  → When I go to the cafeteria to eat, I will conveniently bring a cup of coffee for my roommate.
Habit / every time:
- 每次我去食堂吃饭的时候，都顺便帮室友带一杯咖啡。
  → Every time I go to the cafeteria to eat, I conveniently bring a cup of coffee for my roommate.

Notice there is no special tense inflection on 带; the time meaning comes from 会, 每次, 都, and context.

Why is it just 室友 and not 我的室友? How do we know it’s “my roommate”?

In Chinese, possessives (like 我的, 你的) are often dropped when the possessor is obvious from context.

Here:

我 is the subject.
室友 appears later. In this context, the default interpretation is my roommate.

Saying 我的室友 is also correct:

我去食堂吃饭的时候，顺便帮我的室友带了一杯咖啡。

But it adds a slight sense of emphasis or contrast (for example, if you’ve just been talking about other people’s roommates). In a neutral sentence like this, native speakers are very comfortable omitting 我的.

Is there any tone change or special pronunciation to watch out for in 一杯咖啡 inside this sentence?

Yes, there is a common tone sandhi with 一:

In isolation, 一 is yī (first tone).
Before a fourth‑tone syllable, it is usually pronounced yí (second tone).

Since 杯 (bēi) is first tone, strictly speaking the textbook pattern would keep yī. However, in rapid, natural speech you’ll often hear yí bēi kāfēi as a fluid sequence, and many teachers simply teach yì bēi as a chunk.

The safe, clear pronunciation is:

yì bēi kāfēi (what most learners are taught)
or
yí bēi kāfēi (common sandhi pattern you will hear)

The key is that 杯 keeps its first tone and 咖啡 is kāfēi (first + first), not kǎfēi or other variants.