It's not always important and sometimes Klingon speakers don't even bother to differentiate. For instance, if you are telling a fictional story, perhaps the time frame doesn't even matter.
Most of the time Klingon speakers set the time frame by specifically describing a time. wa'Hu' Suqet "Yesterday, you ran." may' Daleghchugh Suqet "If you see a battle, you will run," (presumably towards the battle). Hoch jaj Suqet "Every day, you run."
For many of the sentences in Duolingo we have left out any time context and so we accept all tenses in the answers (though sometimes we have chosen one to be the "best" answer and if you answer with one of the other tenses, you will also be shown that "best" answer even though it's not really better.
Have you been reading the Tips & Notes. Klingon is different enough from English that it is very difficult to learn just from example sentences. Since Duolingo has hidden the Tips & Notes I want to make sure you know about them and where to find them. If you have not been reading the Tips & Notes, I would like to ask that you review those so we don’t have to continuously repeat the information that we have explained there.
If you are doing the course on iOS or Android, you cannot currently access the Tips & Notes through the app. To access the Tips & Notes, you will have to access the course using a web browser at https://www.duolingo.com/. You can still do it on your mobile device, but you will have to use the web browser instead of the app (or you can do it from a computer). When you click on a Skill, it will expand to reveal a Start button, a key, and a light bulb.
If you click on the light bulb it will reveal the Tips & Notes and give you a detailed explanation of the grammar that is introduced in that Skill. If you have questions after reading the Tips & Notes for any Skills, then please return to the forum to ask your question, explaining what you didn’t understand or what seems contradictory to you.
The tips and notes for this unit are at https://www.duolingo.com/skill/kl/Sentences-1/tips-and-notes, but make sure to go back and read the Tips & Notes from the previous Skill too.