Well if we can't get others' comments time to figure it out for ourselves. I did find a reference that I believe applies to my previous question and alpaca's as well.
"The grammatical difference between those may not be obvious, but in the first one, que translates "that" as a relative pronoun, while in the second de que translates "that" as a conjunction.
Although que can be used as a subordinate or subordinating conjunction when it follows a verb, de que normally is used as a subordinating conjunction following a noun.
So how can you tell if you're translating a sentence of this pattern to Spanish if "that" should be translated as que or de que? Almost always, if you can change "that" to "which" and the sentence still makes sense, "that" is being used as a relative pronoun and you should use que. Otherwise, use de que."
My conclusion- well we don't have a perfect answer because 'that' doesn't really fit. It isn't a conjunction.
So back to research and found this reference-
¿Qué? means "What?"¿Qué es la libertad? What is liberty? ¿Qué estudias? What do you study?
¿De qué? means "About what?" or "Of what?" ¿De qué material es la pluma? What is the pen made of?Literally: Of what material is the pen?
But this doesn't really answer our questions yet so back to the search. I found this little tidbit.
Try not to confuse ¿Qué? and ¿Cuál? The first can be followed by any verb: ¿Qué es esto?, ¿Qué haces? Qué can also be followed by a noun: ¿A qué hora … ?, ¿De qué color … ? ¿Qué tren … ? The interrogative, cuál, on the other hand, can only be followed by forms of the verb ser or estar: ¿Cuál es tu nombre?, ¿Cuál está más cerca?
My impression is that Qué is usually followed by a verb. Notice the sample "de qué color". When Qué is followed by a noun we use a preposition and in our sample it is 'de'. Now lets see if anyone comments.
mcgwn- I said that a word was missing if we don't use the preposition D, in answer of someone else. You explained it with the real words, but as English isn't my first language, my comment was too simple, but I had in mind exactly what you said, no matter the negative votes, that I had. de was missing in the sentence, it was my way to explain it, with my deficient English talking.
I made a research in Internet, every place says de que color? When there's no DE before qué, it's because there's one after, for exemple : qué color de cabello te favorece? or que color de ropa te queda mejor? Also notice that with de que, it seems to be followed by ser or estar.
My first use of "de qué" which I assume is "of what color". What rule makes this necessary? Could you also say "de cual" instead?
I am editing this question because you will see my own detailed answer was posted above. (even though it came after this post). So you might wonder why am I asking this. I would delete this but then the following replies won't make sense.
Qué and Cuál are used moreso like we would use What and Which. For the majority of statements/questions, Qué is used as a question of definition whereas Cuál is used as a determining a distinction between something.
For example, "Qué color" would mean "What color?" like you don't know what a certain color is or you're trying to find someone in a certain colored shirt. "Cuál color" would mean "Which color?" like you're making a choice between red or blue rather than seeking information about what red and blue are.
Based on references provided it would appear that if Qué is followed by a verb that's okay. But color isn't a verb (Is it not the subject with bedsheets being the object). And when asking the question we are really asking "of what color" meaning 'out of all the choices what color is it' I would say 'de que' is appropriate.
You want to avoid translating literally. It has been explained 'de que' so read above comments. However what may not be clear is, it doesn't mean you will translate each and every word. Translate meaning and phrases not words. This can get frustrating because you know the word but it isn't being used as expected. It also means you will make more mistakes. Don't let the mistakes bother you. You are learning. Hope it helps.
Not when we realize that the options shown are not specific to any one sentence. Think of the options as "this may apply to this sentence". Options can help us think through the possibilities but they aren't going to give you exact answer. When we first start DL it seems like the answer is available but as you progress you soon realize it is just a hint.
But I think the hints do change depending on the context of the sentence. In another section, I came across the word sirve which was first translated as works, but in the next question it was translated as serves. The first hint changed because the context was different. That is what I'm suggesting for this question.
What is wrong with interchanging "tus" and "sus"????? I have always grown up interchanging the two, depending how how formal I was trying to be. I'm not a native Spanish speaker, so please, let me know. And if I'm right... Duo, that's one more to add to your list of corrections