1、also用在句中（一般放在be动词和助动词之后，行为动词之前）。
2、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。
3、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。
4、He knows French,and he knows English as well.
