Learn French: Tu allais voir le dentiste, mais tu as reporté le rendez-vous. - You were going to see the dentist, but you postponed the appointment.

Using aller in the imparfait followed by an infinitive like voir is how you express a past intention or plan that didn't happen. The imparfait is perfect for this because it describes an ongoing state or plan that existed in the background before something changed it.

Why does the second half of the sentence switch to the passé composé with as reporté?

This highlights the classic difference between the two past tenses. The intention to go to the dentist was an ongoing background state (imparfait), but the act of actually postponing the appointment was a single, completed action (passé composé) that interrupted that plan.

Is reporté a false friend? It looks like "reported."

Yes, it is a false friend! The verb reporter means to postpone or put off. If you wanted to say you "reported" something, like an incident or the news, you would use a different verb like signaler or rapporter.

I thought a rendez-vous was a romantic date. Can it be used for the dentist?

Absolutely. While rendez-vous can mean a romantic date, it is the standard, everyday word for any scheduled appointment. You use it for doctors, dentists, business meetings, and casual meetups with friends.