条件状语从句时态
条件状语从句时态根据主句决定。主句是一般将来时态，祈使句或情态动词，从句要用现在时态；主句如果是过去的某种时态，则从句要用过去的某种时态。
条件状语常用的引导词是if和unless
1、用if引导：if意为如果。
例句：I donrsquo;t know if it will rain tomorrow. But if it rains tomorrow, Irsquo;ll stay at home.不知道明天是否会下雨，但要是下雨的话，我就呆在家里。
2、用unless引导：unless的意思是如果不除非。
但除了这两个以外，条件状语从句也拥有一些其他的引导词，这些引导词出现频率较低，用法偏复杂，所以不如if和unless知名度那么高。
1. on condition(that)...在条件下
我和祖国一起飞eg.I can tell you the truth on condition that you promi to keep a cret.
You can eat ice cream on condition (that) you won#39;t eat too much.
丰胸按摩方法
2. supposing conj.如果，假如
eg.Supposing it rains,shall we continue the sports meeting?
Supposing anything should go wrong,what would you do then?
3. provided名句大全 conj.假如，除非，以为条件 provided (that) +从句表示一种假设条件。
eg. He will sign the contract provided we offer more favorable terms.
He won#39;t be against us in the meeting provided that we ask for his advice in advance.
国庆4.but for 若非，要不是
eg.But for the rain,we should have a pleasant journey.单项式
But for your help,we should not have finished in time.
5. in ca 如果，万一
eg.In ca I forget, plea remind me about it.
送男生的生日礼物6. as/so long as 只要童年趣事作文450字
eg.As long as yoursquo;re happy,it doesnrsquo;t matter what you do.
中国古代四大凶兽 As long as it doesn#39;t rain, we can go.
