Suppose you want to ask "Why do you have only one microwave?" How would that sentence differ from the one in this exercise?
"Hvorfor har du kun én mikrobølgeovn?"
To show that en is a number rather than an article, you spell it as én, or ét if it is neuter. In spoken Danish, én is pronounced with a lot more emphasis than en so you can hear the difference.
This should accept "why have you got just one microwave" in addition to "why have you just got one microwave".
Can 'mikrobølgeovn' also mean a 'microwave oven', or are those two different things in Danish?
"Microwave oven" was accepted as a translation. I guess "microwave" is just a short form of saying "microwave oven" - you don't use one single microwave to heat food but a device that produces them.
"why do you've" is not possible in English! You often make mistakes in English. Get an educated native speaker to check your sentences.
Is there a difference between kun and bare? For example, could bare be used here?
The difference between kun and bare is the same as the difference between only and just, so in this sentence you could use bare the same way you could also use just in the English sentence.
Så, hvad er forskellen mellem "only" og "just"?
'Why have you only one microwave?' should be allowed. Perfectly acceptable English!
The word kun qualifies one