This was originally posted by Jet.Propelled
I translated the following: هذا مطبخ واسع as “this kitchen is spacious” but Duo says it’s wrong and should be “this is a spacious kitchen”.
Could someone explain how to tell the difference, or is Duo wrong... or am I missing something that makes it obvious?
Comment by EranBarLev
"This kitchen" would be هذا المطبخ, with a definite article.
هدا مطبخ without a definite article means "this is a kitchen". Duo is right.
Reply from Jet.Propelled
Ahhhh... thank you. I was missing something, because Duo hadn’t explained. I wish they gave a bit more background to the grammar in the lessons.
Reply from CloggyMcClogFace
This is explained in the tips section of the lesson. Maybe you're using the app which doesn't have tips? (I have no idea how you can do Duo without tips, which are available on the web version.)
Reply from Captain_Sensible
How very extraordinary. Thanks. I mostly use the iPhone ap, and I have tips for my German and Portuguese lessons, but not for Arabic. I hadn't noticed that tips were available on the browser version!
Reply from Captain_Sensible
You need to pay a lot of attention to the role of the definite article. Indeed: هدا مطبخ واسع = this is a spacious kitchen. هذا المطبخ واسع = This kitchen is spacious. هذا المطبخ الواسع = This spacious kitchen is (something).
Reply from Jet.Propelled
Thank you. That’s the first response that fully have what Duo hadn’t given. We’ve not met using the definite article for adjectives yet, so I couldn’t have paid attention to it even if I’d wanted to.
Reply from Saydobid_Xusanov
That’s the first response that fully has what Duo hadn’t given.
Read the tips of the skill, everything about the articles, especially these examples are explained there in detail. 
Comment from Paul_Oxford
This book is highly recommended. It's simply laid out and covers all the main points:
; Fluent: 
, 
; Getting there: 
; Intermediate: 
; Beginner: 