The subjunctive is a mood. It means is a verb form that does not say that something actually happens, as in the indicative mood, but is used to show someone's attitude about an event or condition, or that the event or condition is being imagined. Verbs that express the subjunctive mood are difficult to identify because they use forms that are also used to express the indicative mood. One verb form used to express the subjunctive is the infinitive, as in "It is important that he leave tonight". In this sentence, "leave" is in the infinitive form to indicate the infinitive. That's why it does not have an "s" on the end, as it would if it were in the indicative mood (e.g.,"He leaves tonight."). However, because most present tense verbs in English are the same form as the infinitive (e.g., I leave, you leave, we leave, they leave), it is only clear that this verb is in the subjunctive when the subject is in the third person singular. Some modals can also be used to express the subjunctive, as in "I wish he would leave". Another way the subjunctive can be expressed is by using a verb tense one time more in the past as the event or condition, as in "I wish he had come earlier", in which the past perfect is used instead of the simple past. Compare this sentence to "He came earlier". In the subjunctive mood, he did not come earlier, but in the indicative mood, he did come earlier. Finally, in "if" sentences, the past tense "were" is used for all persons to indicate the subjunctive, as in "If I were rich, I would buy a bigger house". A lot of Americans do not use this subjunctive form, and say, "If I was rich, I would buy a bigger house."