reason for something / reason for doing something – razón de/para algo / razón para hacer algo
The reason for his resignation is obvious / His reason for
resigning is obvious.
La razón de su dimisión es
obvia / Su razón para renunciar es obvia.
reason (why) / reason (that) – razón por la/el que / razón de que…
The reason (why / that) he didn’t come was that…
La razón por la cual no
vino fue que…
reason to do something – motivo para hacer algo
There is no reason to doubt his sincerity.
No hay motivo para dudar
de su sinceridad.