Translation:Are you Terrans? No, we are not Terrans.
The structure of these exercises is quite clever. It lets you see two different verb forms at once and compare them and learn the pattern and stem. :D
With a one letter error like that the system assumes it was a typing error and not that you thought there was only one Terran. There is a way for us to tell it that this specific error should not be accepted on this specific sentence, but it requires a programmer to go in and individually add that exception to each sentence where we want it. It just doesn't make a lot of sense for us to use the programmers' time like that. We still have much bigger problems in this course that we will ask the programmers to focus on when they have some free time to work on our course. For now, the typo warning will have to do for letting you know you missed that -pu' suffix.