if 分类：连词 定义 如果、是否，引导条件状语从句或宾语从句。 用法 引导真实条件句 引导虚拟条件句 引导宾语从句(=whether) 例句 If it rains, we will stay at home. (真实条件) If I were you, I would go. (虚拟条件) I don’t know if he will come. (宾语从句) 相关术语 whether unless 条件状语从句