Learn Hardcore Chinese: wǒ juéde zhè jiàn shìqíng bù tài jiǎndān.

In Chinese, adjectives can act directly as verbs (predicates). You don’t need a separate verb like 是 (“to be”) in most simple A-not-A descriptions.

So:

这件事情不太简单。
literally: “This matter not-very simple.”

There is no 是 because 简单 itself is functioning as the predicate (“to be simple”).

You only typically use 是 when:

equating two nouns:
他是老师。 – He is a teacher.
or in certain emphasis/topic constructions (e.g. 是……的 structure).

Here, 这件事情 + 不太简单 is a standard “subject + (adverb) + adjective” sentence, so no 是 is needed.

What exactly does 觉得 mean here? Is it “think” or “feel”? How is it different from 想 or 认为?

觉得 (juéde) expresses a personal, subjective opinion or feeling. In English it often translates as:

“I think…”
“I feel…” (in the sense of opinion, not physical sensation)
“I have the impression that…”

In this sentence, 我觉得… is like “I think that…” or “I feel that…”.

Rough comparison:

觉得 – everyday, subjective, often about impressions:
我觉得他很聪明。 – I think he’s smart.
想 – “to think” in the sense of “to consider, to want, to plan”:
我想去中国。 – I want to go to China.
让我想一想。 – Let me think about it.
认为 – more formal, often for more “reasoned” or “objective” opinions:
很多人认为这是个好办法。 – Many people believe this is a good method.

In most conversational situations where you’d say “I think…” in English, 我觉得… is the default choice.

Why is there a measure word 件 between 这 and 事情? Can I just say 这事情?

In Chinese, almost every countable noun needs a measure word (classifier) when you specify quantity, including with 这 / 那.

这 + measure word + noun
那 + measure word + noun

Here:

这 = this
件 = measure word
事情 = matter, affair, thing (abstract)

So 这件事情 = “this matter / this thing (that happened)”.

About dropping the measure word:

这事情 is not standard in modern Mandarin; it sounds dialectal or old-fashioned.
You should say 这件事情 (or 这件事, see below).

Why 件 for 事情? Could I use 个 instead (like 这个事情)?

The “most natural” measure word for 事情 / 事 is 件, especially in the sense of:

matters
affairs
incidents
items (of news, work, clothing, etc.)

So:

一件事情 / 一件事 – one matter
这件事情 – this matter

Using 个 is not strictly wrong, and you will hear 这个事情 in speech, but:

这件事(情) sounds more idiomatic and standard.
Textbooks and exams will strongly prefer 件 with 事 / 事情.

Safe rule: with 事 / 事情, default to 件.

What’s the difference between 事 and 事情? Can I say 这件事不太简单 instead?

Yes, you can absolutely say 这件事不太简单, and it’s very common.

Nuance:

事 (shì) – shorter, very common in speech; means “matter / affair / thing (abstract)”.
事情 (shìqíng) – slightly more formal or complete; often used in both speech and writing.

Often they’re interchangeable:

有件事想跟你说。
有件事情想跟你说。
Both: “There’s something I want to tell you.”

In your sentence, both are fine:

我觉得这件事不太简单。
我觉得这件事情不太简单。

The meaning is effectively the same.

What exactly does 不太简单 mean? How is it different from just 不简单 or 很复杂?

Degree and nuance:

不太简单
literally “not very simple” → sounds mild / soft:
“It’s not so simple / It’s not that simple.”
不简单
literally “not simple” → usually stronger, can mean:
- “not simple / quite complicated”, or
- “remarkable / impressive” (context decides)
很复杂
“very complicated” → directly stresses complexity.

So in your sentence:

不太简单 suggests some difficulty/complexity, but in a moderate, polite way.
If the speaker wanted to emphasize that it’s truly difficult/complex, they might say 很复杂 or 非常复杂.

不太 + adjective is a very common way in Chinese to soften a negative opinion.

Why is it 不太简单 and not 太不简单? What would 太不简单 mean?

Word order changes the meaning:

不太简单
- 不 negates the degree word 太.
- Means “not very simple / not so simple”.
太不简单
- 太 now modifies 不简单 as a whole.
- Feels like “really not simple / extremely not simple / exceptionally special”.

In practice:

不太简单 → mild: “It’s not that simple.” (understatement/softening)
太不简单了！ → often praise or strong emphasis:
- “Wow, that’s really something!”
- “That’s amazing / very remarkable!”

So your sentence is using the soft, moderate form, not the emphatic one.

What’s the function of 太 here? I thought 太 means “too (much)” as in “too expensive”.

太 has two main uses:

Positive / emphatic (without negation):
- 太贵了！ – It’s too expensive!
- 太好了！ – That’s great!
Softening when combined with 不:
- 不太贵。 – Not very expensive.
- 不太好。 – Not very good.
- 不太简单。 – Not very simple.

With 不太 + adjective, it no longer means “too X”; it becomes “not very X / not so X”.

So in your sentence, 不太简单 = “not very simple”, not “too simple”.

Could I say 不是太简单 instead of 不太简单? Is there a difference?

You can say 不是太简单, and it’s grammatical.

Subtle differences:

不太简单
- Very common, smooth, default pattern.
- Feels like a straightforward description: “not very simple”.
不是太简单
- Slightly more emphatic / contrastive.
- Often implies a contrast with an expectation:
  - “(Contrary to what you might think,) it’s not very simple.”
- Structure:
  - 不是 + 太 + adjective

In everyday speech, 不太简单 is more neutral and slightly more common in this “I think it’s not very simple” context. Use 不是太简单 when you want to put a bit more stress on “it’s really not that simple (as you think)”.

Is 这件事情不太简单 a full clause inside 我觉得? Is this like “I think THAT…” in English?

Yes. The structure is:

我 – subject of the main clause
觉得 – main verb (“think / feel (that)”)
这件事情不太简单 – object clause (what you think)

So it’s parallel to English:

“I think (that) this matter is not very simple.”

In Chinese, there is:

no explicit word for “that” here; the entire clause 这件事情不太简单 just follows 觉得.
no comma or special linking word is needed.

Pattern to remember:

我觉得 + [full sentence].
他认为 + [full sentence].
他们说 + [full sentence].

Could I drop some words, like say 我觉得这不太简单? Is that still correct?

Yes, that’s correct and natural.

我觉得这不太简单。
Here, 这 = “this (thing/situation)”, understood from context.

Comparisons:

我觉得这件事情不太简单。 – More explicit and clear: “this matter / this incident”.
我觉得这不太简单。 – Shorter, more casual; depends on shared context.

Similarly, you can also shorten 事情:

我觉得这件事不太简单。 – Very common in speech.

All of these are okay; you choose based on how explicit you want to be and how clear the context already is.

Is there any special pronunciation or tone change in 觉得 or 不太 that I should know?

Two small points:

觉得 (juéde)
- 觉 – second tone: jué
- 得 – neutral tone: de (very light)
  So it’s jué·de, not jué-dé with a full second tone on 得.
不太 – tone sandhi (tone change)
- 不 is normally 4th tone: bù.
- Before another 4th tone, it changes to 2nd tone: bú.
- 太 is 4th tone: tài.

So in natural speech:

不太简单 is pronounced bú tài jiǎndān (2–4–3–1 tones).

This tone change for 不 before another fourth tone is very common (e.g. 不是 → bú shì, 不对 → bú duì).