Learn Hardcore Russian: Мой друг быстро идёт.

The literal translation of the sentence is My friend quickly goes. However, in natural English it is best rendered as My friend is walking quickly.

How does the possessive adjective Мой function in this sentence?

Мой means my and is used as a possessive adjective modifying друг (friend). It agrees in gender, number, and case with друг (masculine, singular, nominative), which is the subject of the sentence.

What role does the adverb быстро play in the sentence?

Быстро is an adverb meaning quickly. It modifies the verb идёт by describing the manner in which the friend is walking.

What is the form and meaning of the verb идёт?

Идёт is the third person singular form of the imperfective verb идти, which means to go or to walk. In this context, it indicates an ongoing action taking place right now.

How would the meaning change if the verb идёт were replaced by ходит?

Using идёт refers to a specific, ongoing action (the friend is walking at this moment), while ходит is typically used for habitual actions or movement in various directions. Replacing идёт with ходит would change the emphasis from a specific instance of walking to a general or repeated action.