Lecture 25: Conditional Sentence ■1 Definition A conditional sentence(or conditional for short) is commonly composed of two parts conditional clause main clause. Despite the many possible sequences of verb forms in conditionals, the following four types represent perhaps the commonest and the most useful ones I. If you heat ice, it melts. (AF# General conditionals II. If we catch the 10 o'clock train, we will get there by lunchtime (真實假設 Open Present or future conditionals) III. If we caught the 10 o'clock train, we would get there by lunchtime.(虚設假設 Unreal Present or future conditionals) IV. If we had caught the 10 o'clock train, we would have got there by lunchtime.(過去虛設假設 Unreal Past conditionals)Lecture 25: Conditional Sentence ◼ 1 Definition ◼ A conditional sentence (or “conditional” for short) is commonly composed of two parts: conditional clause + main clause. Despite the many possible sequences of verb forms in conditionals, the following four types represent perhaps the commonest and the most useful ones: ◼ I. If you heat ice, it melts. （真理General conditionals ） II. If we catch the 10 o’clock train, we will get there by lunchtime. （真實假設 Open Present or future conditionals ） III. If we caught the 10 o’clock train, we would get there by lunchtime. （虛設假設 Unreal Present or future conditionals ） IV. If we had caught the 10 o’clock train, we would have got there by lunchtime. （過去虛設假設 Unreal Past conditionals ）