英语中由if引导的条件句,通常可分为真实条件句和非真实条件句。真实条件句表示该条件有实现的可能,一般用陈述语气;非真实条件句则表示不可能实现的条件,常用虚拟语气。一般来说,虚拟语气表示说话人的愿望、假设、猜测或建议,不表示客观存在的事实常通过谓语动词 The conditional sentences guided by if in English can usually be divided into true conditional sentences and non-true conditional sentences. A real conditional sentence indicates that the condition may be realized, and a statement tone is generally used; a non-true conditional sentence indicates a condition that cannot be realized, and is often used as a subjunctive mood. In general, the virtual tone represents the speaker’s wishes, assumptions, guesses, or suggestions. It does not mean that the objective facts often pass through the predicate verbs.