How do I know whether to say "die" or "dat" in a sentence?
Does the rule have anything to do with relative "het" and "de" terminology? It seems so random to me, or like it depends on context that I'm not seeing.

Question

How do I know whether to say "die" or "dat" in a sentence?
Does the rule have anything to do with relative "het" and "de" terminology? It seems so random to me, or like it depends on context that I'm not seeing.

Answer

I think if you use "De" you need to use "die" and the same for "Het" and "dat".

For example:
De fiets die in de garage staat.
Het boek dat op de tafel ligt.

Answer

http://www.dutchgrammar.com/en/?n=Pronouns.Rl01 Might be a good addition :)

Answer

Plural forms of things and people imply the use of 'die' even with words that imply the use of 'dat' in their singular form:

Het boek (The book)
Het boek dat op tafel ligt (The book that lies on the table)
De boeken die ik heb gelezen (The books that lie on the table)

Het meisje (The little girl)
Het meisje dat daar loopt (The little girl that walks overthere)
De meisjes die daar lopen (The little girls that walk overthere)