(Es necesario que Jack lea las instrucciones.)
Need (necesitar) is usually used as a main verb, but sometimes as an auxiliary verb in the present, e.g.:
| Jack needs to read the instructions. (Es necesario que Jack lea las instrucciones.) |
| She doesn't need to go. (No es necesario que vaya.) |
| She needn't go. (No es necesario que vaya.) |
| We stopped the car because we needed to eat something. (Paramos el coche porque teníamos que comer algo.) |
When we talk about past time, there are two negative forms with different implications, e.g.:
| We needn't have hurried because the show started late. (Nos dimos prisa pero no era necesario, porque el espectáculo comenzó tarde.) |
Needn't have (done) implies that the person did that thing, but it was not necessary.
| Wendy had plenty of money on her, so she didn't need to go to the bank. (Wendy llevaba mucho dinero encima y, por tanto, no tenía que ir al banco.) |
In this case didn't need to go implies that it was not necessary (and in fact Wendy did not go to the bank.).
| Thank you, but you didn't need to wait for us. (Gracias, pero no era necesario que nos esperaseis.) |
In this case, somebody waited, but it was not necessary.
