if条件状语从句（真实条件句）

1.  假设过去（从句是过去的各种时态）

If tall chimneys were built above sea level,the tunnel would be well-ventilated.

2.  假设现在（从句是现在的各种时态）

If he is out,I will call him tomorrow.

If he is working,I won't disturb him.

3.  假设未来（从句是一般现在时）

If it rains tomorrow,we will stay at home.

You will be very lucky if he lets you go without a ticket.

4.  注意主句的变化

if he find something wrong,he may tell you.

If you make a mistake,correct it.

If it rains,I shall take an umbrella with me.

今日暖言：出生在什么样的国家、什么样的时代、有什么样的父母、接受何种教育......这些对个人的生活方式都具有极大的影响力，但事情不可以仅止于此...... Keep on trying and never give up