Learn Romanian: Deși e frig, gheizerul tot erupe. - Although it is cold, the geyser still erupts.

While încă means "still" in a time-related sense (indicating an action is continuing), tot is used here as a concessive adverb. Paired with deși (although), it means "nevertheless" or "anyway," emphasizing that the cold weather doesn't prevent the eruption.

Do I always have to use tot in the main clause when a sentence starts with deși?

It is not strictly mandatory, but it is extremely natural and common in Romanian. Adding tot directly before the verb in the main clause acts as a correlative pair to deși, powerfully reinforcing the contrast between the two halves of the sentence.

Why do we use e (is) with frig here, and how is it different from saying a person is cold?

To describe the weather, Romanian uses the impersonal e frig (it is cold). However, if you want to say a person is feeling cold, you must use a dative construction like îmi este frig or mi-e frig (literally, "to me it is cold").

What gender is the word gheizer, and how does its definite article work here?

Gheizer is a neuter noun. Just like masculine nouns in the singular, it takes the definite article -ul at the end, creating gheizerul. If it were plural, it would take the neuter plural ending -e and the plural definite article -le, becoming gheizerele.