Learn Portuguese (Portugal): Quem tem de preparar o jantar no restaurante? - Who has to prepare dinner at the restaurant?

To express that someone must do something, Portuguese uses the verb ter (to have) followed by the preposition de and the infinitive of the action verb. Here, tem de means "has to", and preparar is the infinitive "to prepare".

Why do we use tem (the he/she/it form) after Quem?

When asking a question with Quem (who), the verb that follows is always in the third-person singular form. This is exactly like English, where we say "Who has..." rather than "Who have...".

Why is there an o before jantar?

In Portuguese, jantar can be both an action verb ("to eat dinner") and a masculine noun ("the dinner"). Using the definite article o (the) makes it clear we mean the noun. It is also very common in Portuguese to use articles before meals, so we literally say "prepare the dinner".

Why is it no restaurante instead of just em restaurante?

In Portuguese, the preposition em (in/at) almost always combines with the word for "the". Since restaurante is a masculine word, we need the masculine article o (the). When we combine em + o, they shrink together to become the word no (at the).