If the subject of
the sentence is not defined - impersonal - the Spanish
uses the passive (as discussed in chapter
8). In English it's then the impersonal you or one:
You have to be quite sure before you get married.
One has to be quite sure before getting married.
To express these kind of general clauses the Spanish
uses hay que. Se tiene que could be used as well, but
our Google-Test showed the following results:
Se tiene que gives
Hay que gives 394,000 hits.
Si hace calor,
hay que ir a la piscina.
= If it's hot one has to go to the swimming
Hay que hacer lo
que dice, porque si no se pone colérico.
= You have to / one has to do what he says,
because if not, he gets choleric.
Este libro, hay que
leerlo cuidadosamente, es bastante difícil.
= This book is to be read carefully it's
Hay que ir a su casa
para saber como está.
= You have to go to his house to know how
he is doing.
Hay que is only used in
the third person singular. It's a left over of the time
when haber was
a full verb and had the meaning of to have to (see chapter
7.1.). It can be also used in past tense.
trabajar mucho. = One had to work
Hubo que decirselo,
pero nadie se lo quería decir.
= One had to tell him, but nobody wanted
to tell him.
decirle que lo deje. = One will have
to tell him that he lets it be.
For information of imperfecto, plusquamperfecto and indefinido