Если контролёр попросит показать проездной, не ищи его слишком долго.

This is a very common difference between English and Russian.

In Russian, after если (if), you can use a future verb when you are talking about a real possible future situation:

• Если контролёр попросит... = If the inspector asks...

So even though English normally uses the present tense after if, Russian often uses the future form here.

Also, попросит is the future form of попросить because попросить is a perfective verb. Perfective verbs do not have a present tense in the normal sense, so forms like попрошу, попросишь, попросит are future.

Because попросить and просить are different aspects:

• просить = imperfective, focusing on the process or repeated action
• попросить = perfective, focusing on one completed request

Here, the sentence means if the inspector asks once or if the inspector requests to see it, so Russian prefers the perfective попросит.

Compare:

• Если контролёр попросит показать проездной...
  = if the inspector asks (on a particular occasion)

• Если контролёр просит показывать проездной...
  would sound like a more habitual or procedural meaning, not what is intended here.

Because it depends on попросит.

The structure is:

• попросить + infinitive = to ask someone to do something

So:

• контролёр попросит показать проездной
  literally: the inspector will ask [you] to show the travel pass

Russian often leaves out the person being asked when it is obvious from context. In English, we might say ask you to show your pass, but in Russian the you does not have to be stated.

Because Russian often omits words that are understood from context.

In this sentence, it is obvious that:

• the inspector is asking you
• не ищи is a command to you

So Russian does not need to say тебя or вас here.

A fuller version could be something like:

• Если контролёр попросит тебя показать проездной...

But that is usually unnecessary.

In this context, контролёр means a ticket inspector or fare inspector on public transport.

It is not the same as the English word controller in most situations. Although the words look similar, here контролёр is the person who checks whether passengers have valid tickets or passes.

So in buses, trams, metro systems, etc., контролёр is the person who may ask to see your ticket or pass.

Проездной is a shortened noun meaning a travel pass, usually one valid for multiple rides or for a period of time.

Originally, it comes from проездной билет:

• проездной = travel/pass-related
• билет = ticket

But in everyday Russian, people often drop билет and simply say проездной.

So:

• показать проездной = show your travel pass

This kind of shortening is very common in Russian.

Не ищи is the imperative form, meaning don’t look for it.

The sentence is giving advice or an instruction:

• не ищи его слишком долго = don’t spend too long looking for it

So the form must be imperative.

Here are the relevant forms of искать:

• ищешь = you are looking / you look
• искать = to look for
• ищи = look for!
• не ищи = don’t look for!

Его refers to проездной.

Since проездной is masculine, the pronoun used for it is его:

• проездной → masculine
• его = it / him in the accusative or genitive form, depending on context

Here it means it:

• не ищи его слишком долго = don’t look for it for too long

This is a good example of how Russian pronouns must agree with the gender of the noun they refer to.

Because слишком means too, so it adds the idea of excess.

• долго = for a long time
• слишком долго = too long

So the sentence does not simply say don’t look for it long. It says don’t look for it for too long, implying that a short search is fine, but an excessive one is not.

Yes, Russian word order is flexible, but the original order is natural and clear.

The sentence is:

• Если контролёр попросит показать проездной, не ищи его слишком долго.

This puts the condition first, then the main instruction:

1. Если контролёр попросит показать проездной = if the inspector asks to see the pass
2. не ищи его слишком долго = don’t look for it too long

You could change the order, for example:

• Не ищи его слишком долго, если контролёр попросит показать проездной.

This is still grammatical, but the original version sounds more natural as advice because it sets up the situation first.

Yes. Ищи is the singular informal imperative, used when speaking to one person with ты.

So this sentence is addressing one person informally:

• не ищи = don’t look for it

If you wanted to address someone formally or more than one person, you would say:

• не ищите его слишком долго

So the difference is:

• не ищи = informal singular
• не ищите = formal singular or plural

Grammatically, yes, it literally says show the travel pass without explicitly saying your.

But in context, it clearly means your pass. Russian often does not use possessives like my, your, his, etc. when they are obvious.

So:

• показать проездной naturally means show your pass here

A more explicit version would be:

• показать свой проездной

But that is usually unnecessary unless the speaker wants emphasis or contrast.

Because the sentence has a subordinate clause introduced by если.

Russian punctuation normally separates the if-clause from the main clause with a comma:

• Если контролёр попросит показать проездной, не ищи его слишком долго.

So the comma works much like in English:

• If the inspector asks to see your pass, don’t look for it too long.

It marks the boundary between the condition and the main instruction.