What do I think, as a parent, when I see this picture?
Tudni akarom, hogy hol van a gyerekem.
I want to know where my child is.
This sentence uses a helping verb. But there is no article. So how do we know whether to use the definite conjugation? I am guessing we use definite conjugation here, because what we are wanting to know is a well defined thing that could be referred to with “azt.”
This is why memorizing sentences is so important. It is one thing to muddle through the logic and understand why something is the way it is after it is presented to you by a native speaker. But it is another thing to produce that kind of logic. It is much easier to play back in your mind a favorite sentence that you have memorized a native speaker use, and use the same pattern to create what you wish to say.
If you understand the reason why, and if you have memorized example sentences, automatic patterns emerge, a sense for what sounds right emerges.