El condicional de presente

[A] Se forma con would/should + infinitivo para la 1ª persona y would + infinitivo para las demás de las personas. 

Afirmativa: I would/I’d work, o bien: I should work; you would/you’d work etc.  

Negativa: I would not/wouldn’t work, o bien: I should not/shouldn’t work; you would not/wouldn’t work etc.

Interrogativa: would/should I work?; would you work? etc.

Interrogativa negativa: should I not/shouldn’t I work?; would you not/wouldn’t you work? etc. 

[B] Se usa

(a) En las oraciones condicionales.

(b) En usos especiales de would y should.

(c) Como un equivalente pasado del futuro simple. would/should tienen que usarse en lugar de will/shall cuando el verbo principal de la oración está en pasado:

• I hope (that) I will/shall succeed. / I hoped (that) I would/should succeed. 
• I know (that) he will be in time. / I knew (that) he would be in time.
• He thinks (that) they will give him a visa. / He thought (that) they would give him a visa.
• I expect (that) the plane will be diverted. / I expected (that) the plane would be diverted.

(Para will/shall, would/should en estilo indirecto, ver más adelante.)