摘要：
each可以用作形容词、副词和代词;every只能用作形容词.Eachofthemhashisownduty.他们各人有各人的义务.Theyeachwanttodosomethin... each可以用作形容词、副词和代词;every只能用作形容词.
Each of them has his own duty.
他们各人有各人的义务.
They each want to do something different.
他们每个人都想做不同的事情.
17. 一般现在时/现在进行时
一般现在时表示经常性的或习惯性的动作或存在的状态,也表示说话者的能力,还有自然现象;而现在进行时表示正在进行或发生的动作（构成方式为am/is /are/+doing）.
I do my homework in the evening.
我在晚上做作业.
I'm doing my homework now.
我现在正在做作业.
现在进行时常与now, these days, at the moment 或Look, listen等词连用;而一般现在时常与often, always, sometimes, usually, every day, in the morning, on Mondays等连用.
We often clean the classroom after school.
我们经常放学后打扫教室.
Look! They are cleaning the classroom .
