Learn French: Quel travailleur est en train de mélanger le ciment et le sable ? - Which worker is currently mixing the cement and the sand?

Quel travailleur est en train de mélanger le ciment et le sable ?

Which worker is currently mixing the cement and the sand?

Breakdown of Quel travailleur est en train de mélanger le ciment et le sable ?

and

quel

which / what (adjective)

mélanger

to mix

être en train de

to be in the middle of (doing)

Questions & Answers about Quel travailleur est en train de mélanger le ciment et le sable ?

Why do we use est en train de mélanger instead of just saying mélange for "is mixing"?

While mélange can mean either "mixes" or "is mixing," the expression être en train de plus an infinitive is used to strongly emphasize that the action is happening right at this very moment. It translates closely to "is in the middle of mixing" or "is currently mixing."

Since the English translation says "mixing", why isn't it en train de mélangeant?

English uses the "-ing" form for progressive actions, but the French expression être en train de must always be followed by a verb in its infinitive (unconjugated) form, like mélanger. You will never use the French present participle (the -ant form) with this expression.

Could I use lequel instead of quel here?

No, because quel is an adjective that must sit right next to the noun it describes (quel travailleur means "which worker"). Lequel is a pronoun meaning "which one" and replaces the noun entirely. If you just wanted to say "Which one is currently mixing...", you would say Lequel est en train de...

Do we really need the second le before sable? Can we say le ciment et sable?

Yes, you need the second article. Unlike English, which often drops words in a list (like "the cement and sand"), French grammar requires you to repeat the article (le, la, or les) before every single noun in a series.