IF-Sätze (Typ III)
CONDITIONAL (IF) - sentences
(past perfect)

If you had left at six, ...
   you would have caught the train.
   (would + have + past participle = conditional 2)

   you could (might,should) have caught the train.
   (auxiliary verb (past) + have + past participle)

   you would not be late now.
   (would + infinitive = conditional 1)

Anmerkung: Der IF-Satz beschreibt jene Bedingung, aus
welcher die Aussage des Hauptsatzes folgt. Bei Satztyp 3
ist die Erfüllung der Bedingung unmöglich (impossible).