"There were five cute cats in the park."
居る（いる）or いた, the word for exist, is different from いった which could be 言った, 行った, or even 要った depending on what you are saying.
いる is a number two verb. This means there is no small つ. 言う and 行く are both number one verbs, and they do have the small つ.
If you know which category the verb is in (1, 2, or 3) it will help with conjugating your endings.
The sentence given uses past informal. Chrabia's way is correct if you wanted to use "ます形."
Both are correct. Learning them both at the same time can be confusing. It is better to start with the polite form.
Thank you, Bethany - this is new to me, I had never heard this explanation before... your explanation was excellent! Makes perfect sense now, so I won't report it as a problem. ;)
One of the problems with Duolingo is that it is not actually a language course, but rather a tool for practice. Every so often, though, something comes across that I just assume is incorrect (I've seen a number of errors in the course so it doesn't surprise me anymore) and I have learned to check here in the forums to see if there is an explanation like yours here.
Thanks again - it's clear to me now! :)
I appreciate your help, but it raises another question. I ended the sentence with ひきいました and it was counted wrong because, it said, I should have used ひきいた。Unless I am just missing something (very possible), it looks to me like the only thing I did wrong was use the more formal language. But both were available on the tiles. So what clue was supposed to tell me to answer with informal?
Is it now a standing feature that the word bank is missing most of the words in the correct solution? 2nd time this happened. And you can't mix word bank and keyboard. I literally twice now have not had half the words in the answer available. I said "are standing" for "is" for example, because you COULD NOT form "imasu" under any circumstances. This is a serious bug.
But I guess びき is a wrong choice. The correct choice for gohiki is 五匹。