Learn Hardcore Russian: Я улыбался, потому что был счастлив.

Улыбался is the past tense, masculine singular form of the verb улыбаться, which means to smile or to be smiling. It is in this form because the subject Я is considered masculine (as would be the case for a male speaker), and Russian requires verb agreement in gender and tense.

Why is there a comma before потому что in the sentence?

In Russian punctuation, a comma is placed before subordinate conjunctions like потому что when they introduce a clause explaining a cause or reason. This separates the main clause from the explanatory subordinate clause, which is similar to the way explanatory or non-restrictive clauses are set off in English.

Why isn’t the subject repeated in the second clause, as seen in был счастлив?

The subject Я is implied in the second clause. In Russian, when the subject remains the same in connected clauses, it is common and acceptable to omit repetition. This keeps the sentence concise while still clearly indicating that the same subject is responsible for both actions.

How does gender affect the past tense forms used in this sentence?

Russian past tense verbs agree with the gender of the subject. Since Я in this sentence is understood to be masculine (reflected in the forms улыбался and был), those masculine endings are used. If the speaker were female, the forms would change to улыбалась and была to reflect the feminine gender.

What does потому что mean, and what role does it play in the sentence?

Потому что translates to because in English. It functions as a subordinating conjunction that introduces a clause providing the reason or explanation for the action mentioned in the main clause. Here, it connects the fact that the speaker smiled to the reason (his happiness).

Why are both clauses in the past tense?

Both clauses use the past tense because the sentence describes events that have already taken place. The main clause Я улыбался describes the action of smiling in the past, and the subordinate clause потому что был счастлив explains the past emotional state (being happy) that caused the smiling.