47.3.5 Ser necesario+ infinitive
Ser necesario, ‘to be necessary’, is less common than hay que+ infinitive or hacer falta
+ infinitive, and much less common than the equivalent English expression ‘to be
necessary’. Its use overall seems more frequent in negative than in positive sentences.
No es necesario repetirlo.
It is not necessary to repeat it.
No es necesario insistir tanto.
It is not necessary to insist so much.
¿Es necesario pagar ahora?
Is it necessary to pay now?
Es absolutamente necesario hacerlo.
It is absolutely necessary to do it.47.3.6 Ser necesario+ subjunctive
Ser necesario may be followed by a complement verb in the subjunctive, expressing
need with regard to a specific person.¿Es necesario que Cristina lo sepa?
Does Cristina need to know it?
Es necesario que vuelvas pronto.
You need to come back soon.
No es necesario que seas tan descortés.
You needn’t be so rude.18.1.1 (p. 84)
47.4 Expressing strong need
To express strong need, we use the following expressions, in constructions similar to
those with ser necesario (see 47.3.6 above). The most common of these are ser
esencial, ‘to be essential’, ser preciso, ‘to be necessary’, ser imprescindible, ‘to be
essential’, ser indispensable, ‘to be essential’, ser fundamental, ‘to be vital’, ‘essential’.
Here are some examples:
Es preciso tener coche/carro (L. Am.).
It is necessary to have a car.
Es indispensable llegar a la hora.
It is essential to arrive on time.
Es imprescindible que nos reunamos.
It is essential that we meet.Expressing strong need 47.4