How long?
is used to ask questions about amounts or periods of time.
Take a look at the following:
How long have you been waiting?' 'Only for about a minute or two.'
How long will the concert last?' 'It should be over by ten o’ clock, I think.'
How much longer?
¿Cuánto (tiempo) más...?
How much longer can you stay?' 'Not much longer. For another ten minutes.
How much longer can he stand/bear running?
How much longer (will it be) until/before…?
¿Cuánto falta hasta que / para que ...?
How much longer (will it be) until I can fly?
How much longer before we are provided with an answer?
How much more time…?
¿Cuánto (tiempo) más ...?
How much more time do we have to provide an answer?
How much more time do you need to wait?
How long (will it be) before /until…?
¿Cuánto (tiempo) falta para ...?
How long will it be before we realise the cost of too much noise?
How long before you are done with your work?
How long until we get there?
How long has it been since...(last)?
verb (past tense)
Cuándo fue la última vez que...? ¿Cuánto hace que no…?
How long has it been since it rained last?
How long has it been since you saw Joe last?
How long has it been since you had a shave last?
How long has it been since you last went to the dentist?
Note the following :
How long has it been since you saw your parents last? Correct.
How long haven´t you seen your parents ? Incorrect
How long is it since…?
¿Cuánto (tiempo) hace que...?
How long is it since you got married? How long is it since you last saw Joe?
How long is it since you last shaved? How long is it since you last ate meat?
GRAMMAR & VOCABULARY