also,too,as well,either,作“也”讲,为副词.下面分别讲述：
一.too,also,as well：都用于肯定句,表示前者怎样后者也怎样.
too：一般放在句尾,可用逗号和前面的句子隔开,也可不用；
also：其位置大多放在be动词、助动词、情态动词之后,实义动词之前；
as well：其位置一般放在句尾,三者可以作同义句转换.例如：
You need to go shopping and I need to go shopping,too.
=You need to go shopping and I also need to go shopping.
=You need to go shopping and I need to go shopping as well.
二.either：用于否定句中,表示前者不……,后者也不……,其位置一般放在句尾.例如：
He doesn”t want any coffee,and I don”t want any,either.
You don”t know the way and I don”t know it,either.
