"Mara understood the Klingons."
Translation:tlhInganpu' yaj mara.
It's not only a problem here, but at other sites that use a single font like Facebook. At least here, if you look carefully you can see a small curl at the bottom of the lower case L. Also, as you get more familiar with the language you start to naturally recognize the patterns of vowels versus consonants and you start to recognize which is which by placement rather than by appearance.
I feel like you may be leaving out information, so I'm gonig to make some assumptions. Please let me know if I have assumed incorrectly. When you say, "still yaj", I think you mean instead of something like jIyaj or Dayaj or some version of yaj that has a prefix, right. So your understanding at this point is that the null prefix (the absence of a prefix) indicates "3rd person subject, no object", right? If that's true, then that is not a correct understanding.
The null prefix (yaj without any prefix on it) can also represent "3rd person subject, 3rd person object" and thus yaj can mean "she understands them". With no other information than just the word yaj there are too many possabilities of what it could mean. If we were in a conversation, the context of the conversation would probably make it clear who the subject was, if there was an object, and who the object is. But if I want to make it more clear, I can specify the subject and object, as in this sentence. There is definitely a clear subject and object in the sentence of this exercise.
Note that there is one exception to the null prefix being "3rd person subject and 3rd person object". If the 3rd person subject is plural and the 3rd person object is singular, there is a special prefix lu- which breaks the pattern of the null prefix.
Because it's so different from English. It's not actually all that complicated, but the fact that it's so different from your base makes it seem very complicated. Are you reading the Tips & Notes? If the Tips & Notes aren't enough to help, feel free to come to these discussions and ask lots of questions.
In case you aren't reading 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 repeat too much of 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.