Learn Hardcore Chinese: tā jīntiān bù lái, huòxǔ shì yīnwèi tài máng le. - He isn’t coming today; perhaps it’s because he is too busy.

不来
- Literally: “not come” / “won’t come”.
- Used for present or future decisions/habits.
- In this sentence, 他今天不来 = “He is not coming today / He won’t come today.”
没来
- Literally: “did not come”.
- Used for past events.
- 他今天没来 = “He didn’t come today.” (Looking back on what already happened.)
不会来
- Literally: “will not come / is not going to come (for sure).”
- Stronger, more definite than 不来.
- 他今天不会来 suggests you are sure he absolutely won’t come.

In this sentence, 不来 fits because you’re talking about (today’s) plan or expectation, not a completed past event.

Why is there a 是 in 或许是因为太忙了? It’s not translated as “is” in English.

Here 是 is working kind of like a link between “perhaps” and the reason:

或许是因为太忙了
Literally: “Perhaps it is because (he is) too busy.”

You could think of the underlying structure as:

或许是因为他太忙了。 – Perhaps it is because he is too busy.

But in natural speech, 他 is often dropped because it’s clear from context.

You can omit 是 in this specific pattern and say:

或许因为太忙了。

Both are acceptable, but 或许是因为… is very common and sounds slightly more natural/complete. The 是 here doesn’t always need a direct translation; it just helps link the guess (或许) to the reason (因为…).

Why isn’t 他 repeated in the second part? Why not say 或许是因为他太忙了?

You can say 或许是因为他太忙了; that is perfectly correct.

However, in Chinese, once the subject is clear from context, it’s very common to omit it in following clauses:

他今天不来，或许是因为太忙了。
Literally: “He today not come, perhaps is because too busy.”

Everyone understands that 太忙 refers to him, because he’s the subject of the first clause. Repeating 他 is not necessary. Omitting repeated subjects is a typical feature of Chinese and makes sentences less repetitive.

What is the role of 因为 here? I thought 因为 usually goes with 所以.

You’re right that a common pattern is:

因为 A，所以 B。 – Because A, therefore B.

For example:

因为他太忙了，所以他今天不来。

But 因为 can also introduce a reason phrase without 所以, especially when that reason is used like a noun phrase after 是:

或许是因为太忙了。
“Perhaps (it) is because (he is) too busy.”

Here, 因为太忙了 is functioning like “because (of) being too busy” as a reason, and 是 links “perhaps” to that reason. So 因为 doesn’t have to be paired with 所以; that pairing is only when you explicitly structure a “because… therefore…” sentence.

What exactly does 太忙了 mean? Is 太 just “very”? And why is there a 了?

太…了 is a special pattern:

太 + adjective + 了

Its most basic meaning is:

“too [adjective]” (often with a feeling, emphasis, or mild complaint)

So:

太忙了 = “too busy” (implying “busier than ideal / more than one would like”).

The 了 here has two common roles:

It completes the pattern 太…了 (this pattern almost always uses 了).
It adds an emotional or exclamatory feel, like:
- 他太忙了！ – “He’s so busy!”

In some contexts, 太忙了 can be translated more neutrally as “really busy” or “so busy” in English, even though literally it is “too busy.” The nuance depends on context and tone.

What does the sentence-final 了 do here? Is it past tense?

No, this 了 is not a simple past-tense marker. Chinese doesn’t have tense the way English does.

At the end of 太忙了, this 了 is:

Part of the 太…了 pattern (“too …”), and
A marker of a change of state or a kind of comment on the situation.

It signals something like: “(He has become) too busy now” / “He’s (really/too) busy (as a current state).”

So in 太忙了:

It does not simply mean “was busy” in the past.
It focuses on the current condition (or a newly realized condition) of being too busy.

So: 了 ≠ past tense here.

What’s the difference between 或许, 也许, and 可能? Could I replace 或许 with the others?

All three express uncertainty (“maybe / perhaps / possibly”), but they differ in feel and usage:

或许
- Often a bit literary or formal, but still used in speech.
- Similar to English “perhaps”.
- Goes well at the start or before 是:
  - 他今天不来，或许是因为太忙了。
也许
- Very common in both spoken and written Chinese.
- Roughly = “maybe / perhaps”.
- You can say:
  - 他今天不来，也许是因为太忙了。 (Very natural.)
可能
- More like “possibly / is possible that”.
- Often behaves more like a modal auxiliary verb:
  - 他今天可能不来。 – He might not come today.
  - 他今天不来，可能是因为太忙了。

In this sentence, you can replace 或许 with 也许 or 可能 without changing the meaning much:

他今天不来，也许是因为太忙了。
他今天不来，可能是因为太忙了。

All are natural. The differences are mostly in tone and style.

Why do we use 来 here without an object? Shouldn’t we say where he is coming to, like “来这里”?

In Chinese, if the destination is clear from context, you can omit it:

来 = come (to here / to the place of the speaker or event).
去 = go (away from the speaker).

In this sentence, the place is understood (e.g., class, a meeting, your house). So:

他今天不来。 = “He’s not coming (here / to the event) today.”

If you want to be explicit, you can say:

他今天不来这里。 – He’s not coming here today.
他今天不来学校。 – He’s not coming to school today.

But it’s not necessary if context already tells you which place you’re talking about.

How can you tell if it’s 他 (he) or 她 (she) when speaking, since they sound the same?

In spoken Mandarin:

他, 她, and 它 all sound the same: tā (first tone).

You can only tell which one is meant from context, because the pronunciation is identical.

In writing, however, they are different characters:

他 – usually “he” or “him” (male or generic person).
她 – “she” or “her” (female).
它 – “it” (things, animals, etc.).

In many cases, even 他 can be used generically for “they / he or she” if gender isn’t important. In your sentence, 他今天不来 could mean “he” specifically, or just “that person” in a gender-neutral way, depending on context.

Can I rewrite the sentence as 因为他太忙了，所以他今天不来? Is that the same?

Yes, you can, and it’s a very standard way to express the same idea:

因为他太忙了，所以他今天不来。
= Because he is too busy, so he’s not coming today.

However, there are some differences in feel:

他今天不来，或许是因为太忙了。
- Emphasizes the uncertainty of the reason: you’re guessing.
- “He’s not coming today; perhaps it’s because he’s too busy.”
因为他太忙了，所以他今天不来。
- States the reason as a fact, not a guess.
- “Because he’s too busy, he’s not coming today.”

So grammatically both are fine, but the original sentence gives a more tentative explanation.

Could 或许 be moved to the beginning: 或许他今天不来，是因为太忙了? Is that okay?

Yes, 或许 is quite flexible in position.

Possible word orders:

他今天不来，或许是因为太忙了。
或许他今天不来，是因为太忙了。
或许他今天不来，因为太忙了。

Differences:

Putting 或许 at the very beginning (或许他今天不来…) makes it clear from the start that the whole statement is tentative.
In the original, 或许 specifically modifies the reason part (是因为太忙了), making it feel like:
“He’s not coming today; perhaps the reason is that he’s too busy.”

All of these are natural; they just shift which part feels more “uncertain” in nuance.

What’s the difference between 他今天不来 and 他今天来不了?

Both can translate as “He’s not coming today,” but the nuance is different:

他今天不来。
- Neutral: he is not coming / he won’t come.
- Focus is on the decision or fact that he is not coming.
他今天来不了。
- Literally: “He is unable to come today.”
- Emphasizes inability or impossibility (schedule conflict, physical limitation, etc.).
- Often implies there’s some reason outside his control.

In your full sentence:

他今天不来，或许是因为太忙了。
already suggests a possible reason.
If you said 他今天来不了，或许是因为太忙了, it would sound like:
“He can’t make it today; perhaps it’s because he’s too busy.”

So 不来 = “doesn’t / won’t come”; 来不了 = “can’t come.”

How do we know this sentence is about “today (in the future)” and not the past, since there’s no tense marker?

Mandarin doesn’t mark tense like English; it relies heavily on time words and context.

In 他今天不来:

今天 – “today” sets the time frame.
不来 – present/future-oriented negative (not the past negative 没).

So together they naturally mean:

“He is not coming today” / “He won’t come today.”

If it were past, you’d normally say:

他今天没来。 – He didn’t come today.

So:

Time word + 不 + verb → usually present/future.
Time word + 没(有) + verb → usually past (didn’t do).

Context (what you’re talking about) then confirms whether it’s about plans, current situation, or already-finished events.