zhè zhèngmíng jìshùrényuán lái le.

The pattern is:

这 + 证明 + 技术人员来了

That is:

• 这 = the subject, meaning this / this fact / this evidence
• 证明 = the main verb, prove
• 技术人员来了 = a whole clause acting as the object of 证明

So Chinese is doing something very natural here: after a verb like 证明, it can put an entire mini-sentence.

Because Chinese often omits that in this kind of sentence.

In English, we say:

• This proves that the technician has come.

In Chinese, after verbs like 说 (say), 觉得 (feel), 知道 (know), 证明 (prove), the next clause usually just comes directly after the verb:

• 这证明技术人员来了

So the idea of that is understood and does not need to be said.

Here, 这 means this, but more specifically it often refers to this fact, this situation, or this evidence.

So it does not have to point to a physical object. It can point to something just mentioned before, such as:

• a piece of evidence
• a result
• something someone observed

That is why 这证明... often feels like This shows... or This proves... in English.

这 can stand alone as a pronoun meaning this. That works very naturally before a verb:

• 这证明... = This proves...

这个 can also sometimes mean this one / this thing, but 这 is more concise and very common in sentences like this.

So before a verb such as 证明, 这 is the most natural choice.

Because 技术人员来了 is a complete clause by itself:

• 技术人员 = technical personnel / technician(s)
• 来 = come
• 了 = completed action / new situation

So 技术人员来了 means the technician(s) came / has(have) arrived.

Chinese often allows this kind of full clause after another verb. In other words, 证明 is not directly modifying 技术人员. It is taking the whole clause 技术人员来了 as its content.

Here 了 marks that the action is completed or that a new situation has come about.

So:

• 来 = come
• 来了 = came / has come / has arrived

In this sentence, 了 shows that the arrival has happened. Without 了, 来 could sound much less definite and might depend more heavily on context.

Not exactly. Chinese does not mark tense in the same way English does.

了 is mainly an aspect marker, not a past-tense ending. It tells you that the action is completed or that there is now a new state.

So 来了 could be translated as:

• came
• has come
• has arrived
• sometimes even is here now, depending on context

The exact English tense depends on the situation, not only on 了.

Because the sentence is mainly focusing on the completed arrival, not on the act of proving.

• 这证明技术人员来了 = This proves that the technician has arrived.

This sounds general and natural.

You can say:

• 这证明了技术人员来了

That puts more emphasis on the idea that it has been proven / this has proven something. It is possible, but the version without 了 after 证明 is often smoother and more neutral here.

By itself, 技术人员 does not clearly mark singular or plural.

It can mean:

• a technician
• technicians
• technical staff / technical personnel

Chinese nouns often leave number to context.

If you want to make it clearly singular, you could say something like:

• 一位技术人员 = one technician

If you want to make it clearly plural, you might add context or a number, such as:

• 两名技术人员 = two technicians

Yes, it functions as a noun meaning technical personnel, technical staff, or sometimes simply technician(s).

It is built from:

• 技术 = technology / technique / technical
• 人员 = personnel / staff / people involved

So literally it is something like technical personnel, but in natural English the best translation may simply be technician or technical staff, depending on context.

来 means come, while 到 often emphasizes arrive / reach.

In many contexts, both can be possible, but they are not identical:

• 来了 = came / has come / showed up
• 到了 = arrived / has arrived

来 usually keeps the idea of movement toward the speaker or reference point, or simply coming over. In everyday Chinese, 来了 is very common when talking about someone showing up.

So 技术人员来了 feels very natural for the technician has come / the technical staff has arrived.

证明 can be both a verb and a noun.

• as a verb: prove
• as a noun: proof, certificate, documentation

In this sentence, it is clearly a verb, because it comes after the subject 这 and is followed by what is being proved:

• 这证明技术人员来了

So here it means proves, not proof or certificate.

Here 了 is usually pronounced with a neutral tone:

• le

So 来了 is pronounced lái le.

This neutral-tone 了 is extremely common after verbs.