also, too, as well, either 辨析

Amy

also, too, as well, either 这些词均含“也”之意

also ： 比too正式一些，语气较重，只用于肯定句，一般紧靠动词。

        I teach five days a week and I also teach evening classes.

too ： 语气较轻，多用于口语，在肯定句中使用，通常位于句末。

            I've been to Paris too.

as well ： 一般不用否定句，通常放在句末，强调时可放在句中。

             I am going to Paris and my brother is going as well.

             You might as well come

either ： 用于否定句，放在句末。

              Mary won't go and Peter won't go either.