Я не могу достать книгу с верхней полки.

Here достать means to reach and get/take something, especially when it is not easy to reach.

So Я не могу достать книгу is not just I can't take the book. It often suggests I can't reach it well enough to get it down.

That is why достать is a very natural verb in this sentence.

Because мочь and уметь mean different kinds of can.

• мочь = to be able to, because circumstances allow it
• уметь = to know how to, to have the skill

In this sentence, the speaker does not have a skill problem. They know perfectly well how to take a book. The problem is that they cannot physically reach it.

So Я не могу достать... is correct.

After modal verbs like мочь (can / be able to), Russian normally uses an infinitive:

• Я могу читать. = I can read.
• Я не могу достать книгу. = I can't reach/get the book.

So могу gives the idea of ability, and достать names the action itself.

This is about aspect.

• достать = perfective: to get/reach successfully, as a complete action
• доставать = imperfective: to be getting/reaching, or to get repeatedly/habitually

With не могу достать, the speaker means I can't manage to get it. That idea of a single completed result fits достать very well.

If you said не могу доставать книгу, it would usually sound like I am unable to get the book repeatedly / in general, which is less natural here.

Because книга is the direct object of достать.

The speaker is trying to get the book, so the noun goes into the accusative:

• nominative: книга
• accusative singular: книгу

For feminine nouns ending in -а, the accusative singular usually changes -а to -у.

Good question. In Russian, negation can sometimes allow or prefer the genitive instead of the accusative. But in modern standard Russian, with a specific, concrete object, the accusative is very common and natural.

So:

• Я не могу достать книгу. = normal, natural: I can't get the book.

Using книги here would sound less neutral and would usually need a special context or a different nuance.

For a learner, книгу is the form to remember in this sentence.

Because the sentence means from the top shelf, not on the top shelf.

• на верхней полке = on the top shelf → location
• с верхней полки = from the top shelf → movement away from the shelf

Since the book is being taken off/from the shelf, Russian uses с.

The preposition с meaning from/off normally takes the genitive.

So:

• nominative: полка
• genitive singular: полки

That is why we get с полки = from the shelf.

Because adjectives must agree with the noun they describe in gender, number, and case.

Here the noun is полки, which is:

• feminine
• singular
• genitive

So верхний must also become feminine singular genitive:

• верхний → masculine nominative
• верхняя → feminine nominative
• верхней → feminine genitive

So с верхней полки is a matching adjective-noun phrase.

Верхняя полка means the upper/top shelf — its position relative to other shelves.

Высокая полка would mean something like a high shelf or possibly a tall shelf, depending on context. It is not the usual way to say top shelf.

So for the top shelf, верхняя полка is the natural phrase.

Yes. Russian often drops subject pronouns when they are clear from the verb form.

• Я не могу достать книгу с верхней полки.
• Не могу достать книгу с верхней полки.

Both are correct.

Because могу already shows I (first person singular), Я is not necessary unless you want emphasis or contrast.

No, Russian word order is fairly flexible. The version here is a neutral, natural order:

Я не могу достать книгу с верхней полки.

But other orders are possible for emphasis, for example:

• Книгу с верхней полки я не могу достать.
• С верхней полки я не могу достать книгу.

These all mean roughly the same thing, but the focus changes slightly. For learners, the original word order is a very good default.

Yes, you could say Я не могу взять книгу с верхней полки, and people would understand you.

But there is a nuance:

• взять = to take
• достать = to reach and get

If the problem is specifically that the book is too high or hard to reach, достать is the better and more idiomatic choice.