1, if the sentence is imagining an event that happened now but didn't actually happen, it will be reversed from the present tense to the past tense:
If+ past tense (clause), 4 modal verbs+verb prototype (main clause)
2. If the sentence imagines an event that will not happen in the future, it is the same as 1, but there are three clauses:
If+ past tense /if+were to do/if+should do, (main clause) 4 Modal verb+verb prototype.
3. If this sentence is imagining an event that happened in the past but didn't actually happen, the past tense will be reversed into the past perfect tense:
If+ past perfect tense, four modal verbs+did.
Pronunciation of extended data: English [? f]； Beauty [? f]？
translate freely
1，conj。 (Table condition) If; Even if; Whether; Hypothesis (table hypothesis)
(1) (Conditional) If
(2) (virtual) if, if.
(3) (expressing concession) Even if
④ Whether or not
(indicating causality) Every time ... (always)
2. Conditions; imagine
References:
Baidu Encyclopedia-If