English - Advanced Grammar - Conditional sentences - Four Conditionals

4 types: (1) ZERO conditional (facts/always true): If + present, present. 'If you heat water to 100°C, it boils.' (always true). (2) FIRST conditional (real/likely future): If + present, will + base. 'If it rains tomorrow, I will stay home.' (possible future). (3) SECOND conditional (unreal present/