Breakdown of Da die Stiftungen großzügig sind, bewundern wir deren Spender.
sein
to be
wir
we
der
who, which, that (relative pronoun; die, das)
bewundern
to admire
Questions & Answers about Da die Stiftungen großzügig sind, bewundern wir deren Spender.
The lesson is about derer vs. deren. Why is it deren here and not derer?
You use deren to refer backwards to a noun that has already been mentioned (in this case, die Stiftungen). You use derer when you are pointing forward to a relative clause that explains who you mean. For example, if you wanted to say "the donors of those who give money" you would use derer: die Spender derer, die Geld geben.
Why do we use deren here instead of the possessive article ihre (their)?
Both are grammatically correct, and you could absolutely say ihre Spender. However, using the demonstrative pronoun deren strongly emphasizes that we are pointing specifically back to the foundations (die Stiftungen). It prevents any ambiguity about whose donors we mean, which makes it very popular in written or slightly formal German.
Why is the verb bewundern right after the comma, instead of wir bewundern?
The entire first half of the sentence (Da die Stiftungen großzügig sind) is a subordinate clause that occupies position 1 of the overall sentence. Because German requires the conjugated verb to be in position 2, the main verb bewundern must come immediately after the comma, pushing the subject wir to position 3.
I originally learned that da means "there". How do I know when it means "since"?