CONDITIONAL SENTENCES. BASIC CONSTRUCTION

1. ZERO CONDITIONALS

Time reference	Verb in Main Clause	Verb in Conditional Clause
all time	Present, usually Present Simple	Present, usually Present Simple

2. FIRST CONDITIONALS

Time reference	Verb in Main Clause	Verb in Conditional Clause
future	will, (might)	Present, usually Present Simple

3. SECOND CONDITIONALS

Time reference	Verb in Main Clause	Verb in Conditional Clause
present or future	would, (could, might)	Past, usually Past Simple

4. THIRD CONDITIONALS

Time reference	Verb in Main Clause	Verb in Conditional Clause
past	would, (could, might) + have + Past Participle	Past Perfect