Learn Portuguese (Portugal): Deves estudar a revolução para o exame. - You must study the revolution for the exam.

Both express obligation, but they have slightly different flavors. Dever (here conjugated as deves) is often closer to "should" or "ought to"—it acts as a strong recommendation or duty. Ter de (like tens de) implies a stricter, unavoidable necessity ("have to"). In this context, both work well, but deves sounds more like strong advice.

Why is estudar not conjugated?

In Portuguese, when two verbs are used together to express a single idea (like "must study"), only the first verb is conjugated. Since deves is already conjugated to match "you" (tu), the main verb estudar stays in its un-conjugated dictionary form (the infinitive).

Why do we use para here instead of por?

You use para when expressing a purpose, goal, or destination. Since studying is done for the purpose of the exam, para is the correct choice. Por is generally used to talk about the cause of an action (meaning "because of"), duration of time, or movement through a place.

Are words ending in -ção always feminine?