由if引导的条件状语从句举例:If you get up early and you can catch the first bus.意思是:如果你早起床你就能赶上第一班车。将此句变成祈使句，祈使句是省略主语you的句子，肯定句是动词原形开头，所以它的祈使句是 Get up early and you can catch the first bus.