A．too 是个常用词,多用于口语,语气较随便.一般用在肯定句中,放在句末,或作为插入语放在句中.例如：
I'm in Row 1,too．我也在第一排.
She,too,is a singer．她也是一位歌唱家.
B．also 是比较正式的用语,语气较庄重.它经常放在句中,位于行为动词之前；位于系动词,助动词或情态动词之后.例如：
Mrs Green can also sing the song in Chinese．格林夫人也能用汉语唱这首歌.
They also have fish shops in that small town．那个小镇上也有鱼店.
C．either 表示“也”时一般只用于否定句,且只置于句末.例如：
I don't know him．Tom doesn't know him,either．我不认识他,汤姆也不认识他.
If you don't go there,he won't go there,either．如果你不去那儿,他也不去那儿.
D．as well 常用于口语,用法和 too一样,通常位于句末,它前面通常不用逗号.例如：
She is a teacher and a singer as well．她是教师,也是歌唱家.
I know Japanese as well．我也懂日语.
E.Neither 两者都不,也不
Neither of my sisters drinks coffee.
我的两个姐妹都不喝咖啡.
He hasn't got a ticket and neither have I.
他没有票,我也没有.
He can neither read nor write.