In English, there are complex sentences where one part is the condition (starts with "if") and the second part is the consequence, the result of what happens if the condition works. We call such sentences conditionals.
Three types of conditionals
a real, feasible condition
if + Present Simple
If you go away, I will miss you.
an imaginary condition that refers to the present or to the future
if + Past Simple
would + infinitive
If you went away, I would miss you.
an imaginary condition that refers to the past
if + Past Perfect
would + have + past participle
If you had gone away, I would have missed you.
Sentences with "I wish"
It would be nice if... — referring to the present or to the future
I wish you were here.
I regret that... — referring to the past
I wish you had called me.
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