She caught the bus immediately on its departure.
where is the mistake, please?
Only "before." The others don't work with "catching" the bus.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.
Last edited by nado92; 22-Mar-2010 at 21:20. Reason: a mistake