When you want to say that you, or someone else, has done the same as someone else, you use **too**, indeed. However, in the negative, if you want to say they have **not** done something, just like someone else has **not** done it, you use **either**. > I enjoyed watching the game. I bet you guys enjoyed it **too**! But: > The game was boring, I could not watch it till the end! I bet you guys could not **either**! If you would use **too** in a negative sentence, it means something else: > I scored 1000 points in this game. I bet you cannot do it too! Notice that now, I _did_ score those points, and I am betting that someone else can **not** do it.