Learn Russian: Эту старую стену нельзя разрушить, она из железа. - This old wall cannot be destroyed, it is made of iron.

This perfectly demonstrates the current lesson! When you use нельзя with a perfective verb like разрушить, it means the action is physically impossible to successfully complete. If we used the imperfective разрушать, it would mean destroying the wall is prohibited or forbidden. Since the wall is made of iron, it is about impossibility, not rules.

Why is the sentence starting with Эту старую стену in the accusative case, if it translates as the subject in English?

In the English translation, the wall is the subject of a passive sentence. But literally, the Russian sentence is structured as 'It is impossible to destroy this old wall.' The wall is the direct object receiving the action of the verb разрушить, so эта старая стена changes to the accusative эту старую стену.

Why use она for 'it' instead of оно?

The pronoun она refers back to the word for wall, стена. Because стена is a feminine noun, you must use the feminine pronoun to say 'it', regardless of whether the object is a living thing or an inanimate object.

What grammar rule is at work in the phrase из железа?