How to use “so” and “neither” to show you agree with or have had the same experience as someone. For example, if your friend says, “I like pizza”, you can answer, “So do I” to agree with them. If your friend says, “I can’t whistle”, you can answer, “Neither can he” to refer to someone else. As you can see, “so” and “neither” can be used with different verbs and different subjects.