too通常放在句尾，也可放在主语之后，可用逗号与前边的成分分开。
If they go to the park ,I will go,too.
如果他们去公园，我也去。
We too must play our part .
我们也必须尽自己的责任。
If you want people to treat you nicely,then you have to treat them nicely ,too.
如果你想人们对你友好，那么你也应该友好的对待他们。
as well多用于口语，一般放在句尾，不用逗号与句子分开
She can dance and she can play the piano as well.
她会跳舞也会弹钢琴。
Why don't you come along as well?
你为什么不一起来？
