Put Modals into the past.

Question

Hello, I am studying the Modals and now I am wondering how can they be put into the past. My head is about to explode. Any help is appreciated.

Could / Should / Would seems to be easy to "transform":

• I could sing that song. - Podría cantar esa canción. (present possibility)
• I could have sung that song. - Podría haber cantado esa canción. (that didn't happen)
  
• You should be there. - Deberías estar allí.. (It is convenient for you)
• You should have been there. - Deberías haber estado allí (You didn't keep your word)
  
• They would answer the question. - Ellos contestarían a la pregunta. (Just ask and you'll see).
• They would have answered the question. - Ellos hubieran contestado a la pregunta. (Now it's too late).

Can (always relates to present)

• I can lift 50 pounds. Puedo levantar 50 libras. (present ability)
• I can could have lifted 50 pounds.

May

• Visitors may not use this car park. - Los visitantes no pueden usar este aparcamiento. (permission)
• Visitors may not have used this car park. - Los visitantes puede que no hayan usado este aparcamiento (Uncertainty because I don't know whether they used the car park or not).

Might

• It might be a little more expensive but it's much better. - Puede que fuera un poco más caro, pero es mucho mejor. (It actually was a little more expensive).
• It might have been a little more expensive. - Podría haber sido un poco más caro. (We could have been charged more. We got a good price)

Will / Shall (auxiliar for the future, suggestions and orders)

• You will be the first to know. - Serás el primero en saberlo.
• You will would have been the first to know.
• You shall do as you are told. - Harás lo que se te de diga.

Used to (always in the past)

• I used to play football at school. - Solía jugar a fúbol en la escuela.

Must

• You must respect your parents. - Dedes respetar a tus padres.
• You must have done that. - Debes de haber hecho eso. (If you cannot remember, you were probably drunk).

Ought to (just like should)

• You ought to be there. - Deberías estar allí.. (It is convenient for you)
• You ought to have been there. - Deberías haber estado allí (You didn't keep your word).

My impression is that Modals cannot be always put into past; and when possible, it depends on its specific usage. In addition, some of them seem to change its meaning completely when transformed into the past tense (like may). What do you think?

Please, correct my translations.

"I could have lifted 50 pounds." not, "I can have" - rac1, Sep 19, 2013

I see what you mean. Thanks. - RelaxingCup, Sep 19, 2013

Answer 1

rac1 is correct -

Can always relates to the present so is one of the Modals that is not used in the "past"

"Will" is another one. It is used to make the simple future.

"I may / might have done it" are ok - means "I am not sure if I did do it"

"used to" is always in the past - it is the only way an English verb can be put into the "imperfect".

"shall" is used to make the future tense (so cannot be in the past) and to make suggestions.

"must have" is ok. I must have done it but I can't remember. It changes meaning in the past.

"ought to have" is ok - I ought to have done but I didn't.

Update

shall - is used to make a suggestion - shall we cross the road?

and the future - "I shall return" - it is more of a promise than "I will return" which is a prediction. It can also be used as a command as suggested "You shall do your homework"

Thaaaank you very much! :) - RelaxingCup, Sep 19, 2013

Answer 2

I've modified my question by completing the eleven Modals. I hope it's better (and more useful) now. Thank you ian-hill and rac1.

It is better amigo. - ian-hill, Sep 20, 2013