关于英语中的“也”too ; as well; also; either; as well as; 它们之间的用法和区别

also用在句中（一般放在be动词和助动词之后,行为动词之前）.
she also is good at English.
she also like English.
too 多用于口语,位于句未或句中,只用于肯定句,其前常有逗号.
They are students,too.=They,too,are students.
否定句为They are students,either.
as well 用于肯定句,通常位于句中或句尾.
He knows French,and he knows English as well.

too, as well和 also用于肯定句和疑问句，too和as well多用于口语，一般放在句末，而also多用于书面语，一般放在句中与动词连用。either 用于否定句和否定的疑问句，往往放在句末。如：
He went there too.
He didn't go there either.
I like you as well.
I ...