Remember that conditionals become less real or true as they ascend from ZERO to
THIRD, it is for this reason SECOND and THIRD conditionals are considered ‘unreal conditionals.’
The unreal conditionals can be mixed, meaning that the tense in the main clause
(ACTION) can be different from the conditional clause (CONSEQUENCE).
There are two types of mixed conditional THIRD/SECOND and SECOND/THIRD.
They are called this because the THIRD/SECOND mixes the first part (ACTION) of the
THIRD with the second part of the SECOND (and vice versa).
THIRD/SECOND – used to express that a different past would have produced a different present.
IF + PAST PERFECT + WOULD + INFINITIVE
IF I had studied harder, my parents would be happy.
IF I had added more sugar, this cake would be delicious.
IF I hadn’t stopped, I would be home by now.
SECOND/THIRD – used to express that the present situation or result justifies, demonstrates or confirms a fact or truth from the past.
IF + PAST SIMPLE + WOULD + PRESENT PERFECT
IF I woke up earlier, I would have arrived on time.
IF I went left instead of right, I wouldn’t have gotten lost.
NOTE: In these conditionals you can replace WOULD with other modal verbs (could, might
etc) to express different degrees of certainty, permission or recommendation.
IF he had the money, he could have been on this trip.
IF he had bought a lottery ticket, he might be a millionaire now.
UNLESS and WISH with CONDITIONALS
Unless is like a negative form of IF, it literally means ‘IF NOT’ and can be used in place of IF NOT or where IF is followed by a negative, unless it incorporates that negative.
I wouldn’t have phoned him if you hadn’t suggested it.
I wouldn’t have phoned UNLESS you had suggested it.
FIRST CONDITIONAL + UNLESS
You’ll get sick if you don’t eat your vegetables.
You’ll be sick UNLESS you eat your vegetables.
SECOND CONDITIONAL + UNLESS
I wouldn’t eat vegetables if I wasn’t really hungry.
I wouldn’t eat vegetables UNLESS I was really hungry.
THIRD CONDITIONAL + UNLESS
I wouldn’t have been able to jump if you hadn’t done it first.
I wouldn’t have been able to jump UNLESS you had done it first.