"You are looking at the dogs."
Translation:Tu es en train de regarder les chiens.
Please tell me why is it necessary to insert "en train de" -- tu es regarder les chiens -- is correct. Isn't it?
There is no continuous tense (are looking) in French. "Tu es regarder" is not correct.
The phrase "être en train de" is used to denote an action that is happening at this precise moment. So right now, "you are looking at the dogs."
I think in this same unit, we had a sentence, along the lines of they like to look at the elephants, using the infinitive regarder. So for example, this could never be translated as like looking at the elephants?
You can translate "aime regarder" as both "like looking" and "like to look".
OK, but then why did you say above there is no continuous tense in French? What am I missing?
The English continuous tense is a conjugated "to be" + ____ing. For example, "are looking", "were eating", "will be dancing", etc. There is no word-for-word construction like that in French. They simply conjugate the verb: for example, "regardez", "mangeais", "dansera", etc.
The French do have words for the English "ing" verb forms, but they're not combined with "être" (to be) to form a tense. So things like "êtes regardez", "étais mangeais", "sera danser" are nonsense.