Ne možemo otvoriti prvu kutiju, a kamoli razumjeti mehanizam.

A kamoli is a fixed expression meaning let alone or much less.

It introduces something that is even less likely, harder, or more impossible than the first thing mentioned.

So the logic is:

• we cannot do the first, easier thing
• let alone the second, harder thing

In this sentence, opening the first box is presented as difficult enough; understanding the mechanism is even further out of reach.

You should learn a kamoli as a whole expression, not by translating each word separately.

Not really.

Croatian a can sometimes be translated as and, but very often it has a contrastive feel, closer to but, while, or whereas. In a kamoli, it is part of the set phrase, so it is best to understand the whole combination together.

So in this sentence, a is not a simple additive and. It helps set up the contrast: we can’t even do X, let alone Y.

Ne možemo means we cannot or we are not able to.

Breakdown:

• moći = to be able, can
• možemo = we can
• ne možemo = we cannot

This is the 1st person plural present tense form of moći.

Croatian often uses this structure exactly like English can + verb:

• možemo otvoriti = we can open
• ne možemo otvoriti = we cannot open

Because Croatian usually does not need subject pronouns when the verb ending already shows who the subject is.

Here, možemo already tells you the subject is we.

So:

• možemo = we can
• mi možemo = we can, with extra emphasis on we

Using mi is possible, but it would sound more emphatic. In a neutral sentence, Croatian normally leaves it out.

Because after the modal verb moći you normally use an infinitive.

That is the same basic pattern as in English:

• can open
• can understand

Croatian:

• možemo otvoriti
• možemo razumjeti

In the second part of the sentence, the modal verb is understood rather than repeated:

• Ne možemo otvoriti prvu kutiju, a kamoli razumjeti mehanizam.

This is understood as something like:

• Ne možemo otvoriti prvu kutiju, a kamoli možemo razumjeti mehanizam.

But Croatian normally leaves the repeated možemo out because it is already clear from the context.

This is an aspect question.

• otvoriti is perfective
• otvarati is imperfective

Here, otvoriti is natural because the meaning is about successfully completing the action: to open the box.

So the sentence is talking about the result:

• we can’t open the first box

not about an ongoing or repeated process such as:

• opening boxes in general
• trying to open it repeatedly
• being in the middle of opening it

That is why otvoriti fits well here.

Because kutija is the direct object of otvoriti, so it must be in the accusative case.

Dictionary form:

• prva kutija = the first box

Accusative singular:

• prvu kutiju

Both words change because the adjective must agree with the noun:

• prva → prvu
• kutija → kutiju

So:

• otvoriti prvu kutiju = to open the first box

Because mehanizam is a masculine inanimate noun, and in Croatian those nouns often have the same form in the nominative and accusative singular.

So:

• nominative: mehanizam
• accusative: mehanizam

Even though the form looks unchanged, it is still functioning as a direct object here:

• razumjeti mehanizam = to understand the mechanism

This is very common with masculine inanimate nouns.

Because a is connecting two coordinated parts, and Croatian normally places a comma before a when it joins clauses or clause-like units in this kind of structure.

So the punctuation is standard:

• Ne možemo otvoriti prvu kutiju, a kamoli razumjeti mehanizam.

The comma helps mark the pause and the contrast between the first statement and the stronger follow-up.

Because a kamoli works by moving from a less extreme statement to a more extreme one.

The first part sets a baseline:

• we cannot even open the first box

Then the second part raises the bar:

• understanding the mechanism is even harder

So the order matters. The first action is presented as the more basic or more attainable one, and the second as even less possible.

That is exactly the kind of scale that a kamoli expresses.

No. A kamoli is quite flexible. It can be used with different kinds of words or phrases, as long as the meaning is let alone / much less.

For example, it can connect:

• nouns
• verb phrases
• larger parts of a sentence

The key idea is always the same: if the first thing is already impossible, unlikely, or insufficient, the second thing is even more so.

So in your sentence it connects two infinitive phrases:

• otvoriti prvu kutiju
• razumjeti mehanizam

But the expression itself is not limited to infinitives.