This document discusses the different types of conditional sentences in English:
- Zero conditional describes things that are always true.
- First conditional talks about future actions dependent on future conditions. It uses present tense for the condition and will for the result.
- Second conditional talks about unlikely present or future situations. It uses past tense for the condition and would for the result.
- Third conditional talks about imaginary past actions where the conditions were not met. It uses past perfect for the condition and would have for the result. Each conditional has a specific grammatical structure and usage.