"A carrot can be white."
Translation:Karoto povas esti blanka.
There are definitely exceptions, but a good rule of thumb is that you shouldn't have multiple non-infinitive verbs in a row. :)
That would make the povas into a verb and you cannot 'white'. You need to have the 'to be' in there to show that it IS white. To English speakers, Esperanto does shorten some things down, however not this much. In other areas, Esperanto speaks as an olde language and adds more into it, making it almost poetic.