意义：用于阐述事实.x0d结构：If + subject + simple present,subject + simple present.x0dSubject + simple present if + subject + simple present.x0d例句：If I see a spider,I get panicky.x0dI feel claustrophobic and immediately want to get out of if I enter an enclosed space.x0d第一条件句First Conditionalx0d意义：表达一个动作后的结果x0d结构：If + subject + simple present,subject + will + verb.x0dSubject + will + verb + if + subject + simple + present.x0d例句：If we move the office to the 15th floor,I'll resign.x0dI'll probably have another panic attack if I see a spider.x0d第二条件句Second Conditionalx0d意义：用于表达一个假设情况后的结果.x0d结构：If + subject + simple past,subject + would + verb.x0dSubject + would + verb + if + subject + simple past.x0d例句：If I didn't suffer from a fear of flying,I would travel more.x0dI would consult a doctor if I had a phobia.x0d第三条件句Third Conditionalx0d结构：If + subject + past perfect,subject + would have + past perfect.x0d改成第三条件句：If she hadn't been ill,she would have gone to work.