Learn Hardcore Chinese: yīnwèi wǒ juéde jīntiān tài máng le, suǒyǐ wǒ méiyǒu qù gōngsī. - Because I feel today is too busy, I didn’t go to the company.

With both: 因为…，所以… is very common and clear: 因为我觉得今天太忙了，所以我没有去公司。
With only 因为: 因为…，…: 因为今天太忙了，我没有去公司。
With only 所以: …，所以…: 我今天太忙了，所以没去公司。 Don’t use standalone 因为… without finishing the sentence; it sounds incomplete.

Can I put the result first and the reason second?

Yes. 我没有去公司，因为我觉得今天太忙了。 This order is very natural in speech and writing.

Why is there 了 after 忙 in 太忙了? Is that past tense?

It’s not past tense. The 了 here is the modal particle in the set pattern 太…了, which expresses an excessive degree or exclamation (too/extremely). It does not mark completion or past time.

Can I drop 了 and just say 太忙?

In standalone predicative use, you normally keep 了: 今天太忙了 sounds natural; 今天太忙 is usually avoided.
You might see 太忙 before a noun (太忙的日子) or directly before a verb as an adverb in some styles (太忙没时间), but for simple statements, stick with 太忙了.

What’s the difference between 太忙了 and 很忙?

太忙了: “too busy” (excessive/complaint).
很忙: “very busy” (strong but not excessive). If you don’t want the “too much” nuance, use 很忙.

Why use 觉得 here? Could I just say 我今天太忙了?

我觉得今天太忙了 frames it as your opinion/judgment (“I think/feel…”).
我今天太忙了 states it directly as a fact about you today. Both are fine; choose based on whether you want to hedge as an opinion.

What’s the difference among 觉得, 认为, 以为, and 感觉?

觉得 (juéde): everyday “think/feel” (subjective). Best choice here.
认为 (rènwéi): “hold the view that” (more formal/objective reasoning). 我认为今天太忙了 is grammatical but a bit stiff in daily talk.
以为 (yǐwéi): “thought (but was mistaken).” Use only for a belief that turns out wrong.
感觉 (gǎnjué): “feel/sense” (can be verb or noun); more about sensation or general impression. 我感觉今天很忙 also works, slightly more emotive.

Where should I put 今天? Are these all okay?

All are grammatical but differ in focus:

我觉得今天太忙了: You think today (as a time period/schedule) is too busy.
我今天觉得太忙了: Today, you feel too busy (focus on your feeling today).
今天我觉得太忙了: Emphasizes “today” first for topicalization. Chinese often follows Subject + Time + Place + Verb; but time can also front the sentence for emphasis.

Can “today” be “busy”? Isn’t that odd?

In Chinese, 今天太忙了 is idiomatic and means “today is too busy (for me/for the schedule).” It’s completely natural.

Why 没有去 and not 不去?

没(有)去: not go (actual non-occurrence in the past) → “didn’t go.”
不去: not go (habitual, refusal, or future decision) → “don’t/won’t go.” Here you’re describing what happened (or didn’t happen), so use 没(有).

Is there any difference between 没去 and 没有去?

They mean the same. 没有 can sound a bit more emphatic or careful; 没 is more colloquial.

Why not say 去了 in the second clause? Where is the past marking?

In Chinese, past is often inferred from context (e.g., 今天, the situation) and from negation with 没(有). You can’t use perfective 了 when negated: it’s 没(有)去, not 去了 or 没去了.

Should I repeat 我 in the second clause after 所以?

Not required. Subject drop is fine when it’s clear:

With repetition: …，所以我没有去公司。
Without repetition: …，所以没有去公司。 Both are natural.

What’s the difference between 去公司, 上班, and 去公司上班?

去公司: go to the company (movement to the workplace).
上班: be on/at work (the act/state of working).
去公司上班: go to the company to work (explicitly not remote). Example: 我今天没去公司，但我在家上班。

Should I say 公司 or 办公室?

公司: the company/workplace as an organization/site (often “the office” in English).
办公室: the office room. 去办公室 = go to the office room (e.g., inside a school or company). If you mean “go to work/the workplace,” 去公司 is more typical.

What about 到 vs 去 (e.g., 到公司 vs 去公司)?

去 focuses on going toward somewhere.
到 focuses on arriving.
So:
没去公司: didn’t go (likely never set off).
没到公司: didn’t arrive (maybe set off but failed to arrive). Both are valid with slightly different implications.

Could I say this more logically as a prediction: “I thought today would be busy, so I didn’t go”?

Yes, add 会 for a predicted future:
因为我觉得今天会很忙，所以我没有去公司。
That reads “Because I thought today would be very busy, I didn’t go to the office.”

Any pronunciation tips (tone sandhi, neutral tones) in this sentence?

觉得 (juéde): second syllable de is neutral tone.
所以 (suǒyǐ): underlying tones are 3–3; in fluent speech, the first 3rd often surfaces as a rising contour (3–3 sandhi), so you may hear it as a light rise on suǒ.
了 (le): neutral tone.
没有 (méiyǒu): 2–3; the third tone may be realized as a half-3 in connected speech.

Is 我没有去过公司 a valid alternative?

It changes the meaning. 没去过 means “have never been (at any time before).”

我没有去公司 = I didn’t go to the office (on that occasion).
我没有去过公司 = I have never been to the office (ever). Not the same.

Is the comma before 所以 correct? Any punctuation rules?

Yes. In Chinese, you normally use a comma to separate the reason and result clauses:

因为…，所以…
…，因为… A semicolon can appear if the clauses are long or parallel, but a comma is standard here.