Relative clauses with 'was'
I have a question about how relative clauses beginning with "was" interact with prepositional adverbs. Do you have to spell out the whole prepositional phrase, or can you use the prepositional adverb. For example, what would be the proper way to form this sentence?
Ich habe Angst davor, was passiert ist.
Ich habe Angst vor dem, was passiert ist.
Danke im Voraus!