also “也，而且”，较为正式,只用于肯定句,通常位于be 动词、助动词或情态动词后，行为动词前。

He also came. 他也会来。

He is also a good and healthy boy.他也是一个既善良又健康的男孩。

This is an American car.That is also an American car.

She can also play the piano.她也会弹钢琴。

有时放于句首，用“，”隔开，表示强调。

Also, you must come to my home, of course.当然，你也必须来我家。

too“也”，多用于口语，常用于肯定句句末，和句子的主干部分用”，”隔开。

She is French. I am French, too. (=I am also French.)她是法国人，我也是法国人。

He is a teacher, too.他也是一名老师

Too也用于固定搭配，多用于口语。

I like this song. Me to.(=I like it ,too.)

as well 也常用于肯定句中，总是放在句末，但是前面不用“，”。

My grandpa likes doing some kung fu, my grandma likes it as well.

我爷爷喜欢练武术，我奶奶也是。

For breakfast, she has bread and milk, and I have them as well.

早餐，他吃了面包和牛奶，我也是。

either“也不”， 常用于否定句和疑问句中，放在句末，和句子的主干部分用”，”隔开。

I am not Japanese, either.我也不是日本人。

I don’t like playing the piano, either. 我也不喜欢弹钢琴。

Is your friend tall, either?