如何区别if 和when引导的状语从句if i have time,i will help you.是不是也可以说成when i have time,i will help you.好像很多if 和when 都可以互相替换..但答却只能是其中的一个..它们的区别是怎么样?如when my mother is out,i have to take care of my sisters.and if my mother is out,have to take care of my sisters.
问题描述：
如何区别if 和when引导的状语从句
if i have time,i will help you.是不是也可以说成when i have time,i will help you.好像很多if 和when 都可以互相替换..但答却只能是其中的一个..它们的区别是怎么样?如when my mother is out,i have to take care of my sisters.and if my mother is out,have to take care of my sisters.
答
首先要知道if引导的是条件状语从句,而when引导的是时间状语从句.从语法角度是有严格区别的.当when引导的时间在将来时,通常可以和 if互换.从词义角度看,if是如果,偏向于虚拟语气,多用于对未来的假设或推测,when多用于一般描述或许诺,条件满足即发生.