Want, can, must and the imperative

Formation

Querer (to want), poder (can, may), saber (to know how to) and dever (should, must) are followed directly by an infinitive, with no word for English “to”: quero sair, posso entrar?, sei nadar, devo estudar. Ter de (to have to) is followed by the infinitive after de: tenho de trabalhar. In the negative, não is placed before the conjugated verb: não posso ir. The present of querer, poder and saber is given in “The present of irregular verbs: ser, estar, ter, ir, fazer”; dever is a regular -er verb.

Use

Querer expresses a wish, and may also be followed by a noun: quero um sumo. Poder expresses possibility or permission: Posso entrar? (“May I come in?”). Saber + infinitive expresses a skill that has been learnt: Sei nadar (“I can swim”). Ter de expresses obligation: Tenho de sair cedo. Ter que (tenho que sair) is also heard and is correct, but ter de is the form recommended in Portugal. Dever expresses advice or a softer obligation, like “should”: Deves descansar.

Formation

Two set forms are used for polite requests: queria (“I’d like”), followed by a noun or an infinitive, and podia (“could you”), followed by an infinitive. They are forms of querer and poder in a past tense, used here with a present meaning.

Use

In a café, a shop or a hotel, queria is the usual way of asking for something: Queria um copo de leite, por favor. Quero in a request sounds abrupt, like “I want” in English. Podia…? asks someone politely to do something: Podia repetir, por favor? Pode…?, in the present, is also polite.

Formation

Saber is irregular in the eu form (sei), conhecer is written with ç in the eu form (conheço), and conseguir changes its vowel in the eu form (consigo, consegues, consegue, conseguimos, conseguem).

Use

Saber is used for a fact or a piece of information, before onde, quem, quando or que, and before an infinitive for a skill. Conhecer is used for a person or a place one has met or visited, and takes no preposition before a person: conheço a Ana. Conseguir + infinitive expresses what one manages to do, often with an effort or with the senses: Não consigo ouvir (“I can’t hear”).

Formation

To a friend (tu), the imperative is the third person singular of the present, that is the tu form without its final -s: entras → entra, comes → come, abres → abre. The tu forms of dizer, fazer and ver are short, the third person singular of the present: diz, faz, vê; lê (ler) and ouve (ouvir) are formed the same way. To a person addressed politely (o senhor, a senhora, você), the form is built on the eu form of the present: the -o is replaced by -e in -ar verbs and by -a in -er and -ir verbs: entro → entre, como → coma, abro → abra, faço → faça, digo → diga, vejo → veja, ouço → ouça, leio → leia. Before -e, c is written qu and g is written gu: fique, chegue. To several people (vocês), -m is added to the polite form: entrem, comam.

Use

The imperative is used for an instruction, an invitation or a piece of advice; with por favor, it is polite. Two set forms are used every day: senta-te / sente-se (“sit down”) and desculpa / desculpe (“sorry, excuse me”). Olha / olhe is also used to catch someone’s attention, like English “look” or “listen”. These forms are used in the affirmative; a negative instruction is formed differently.