No Dangling Prepositions
In English, we often leave prepositions at the end of a clause, like "The scratch that you complained about." In Portuguese, prepositions are never left dangling. If a verb requires a preposition, it must go directly before the relative pronoun que.
Using "de que"
Many common Portuguese verbs require the preposition de (such as precisar de, to need, or gostar de, to like). When describing a noun using one of these verbs, you must use de que.
| The scratch that you complained about is on the hood. | O arranhão de que te queixaste está no capô. |
| The service that I need is very expensive. | A revisão de que preciso é muito cara. |
| I wanted to negotiate the car that we liked, but the mileage is high. | Queria negociar o carro de que gostámos, mas a quilometragem é alta. |
Using "em que"
Similarly, verbs that require the preposition em (like reparar em, to notice, or tocar em, to touch) will use em que.
| Did the mechanic see the scratches that I noticed? | O mecânico viu os arranhões em que eu reparei? |
| The hood that he touched is hot. | O capô em que ele tocou está quente. |
Note that em que is also commonly used to mean "where" or "in which" when talking about physical locations, such as a dealership (o stand).
| The dealership where the mechanic works is reliable. | O stand em que o mecânico trabalha é fiável. |
Using "a que" and "com que"
This rule applies to all short prepositions. If a verb or phrase uses a (to/at) or com (with), simply place it before que to connect your ideas.
| The clutch that you are used to is different. | A embraiagem a que estás habituado é diferente. |
| The tool that I fixed the clutch with disappeared. | A ferramenta com que consertei a embraiagem desapareceu. |