Question

1. after world war ii, young people in america were buying more than one - third of all records sold.
2. what did the magnetic tape recorder replace in the postwar era?

Explanation:

1. For question 17: Post-WWII, American youth were the dominant consumer of records, purchasing over one-third of all sold units, so the initial "False" is incorrect.
2. For question 18: In the postwar era, magnetic tape recorders replaced the acetate disk-based recording devices (like disk cutters) that were previously used for audio recording, as tape offered better sound quality, easier editing, and lower costs.

Answer:

1. True
2. It replaced acetate disk recording devices (disk cutters) used for audio recording.