1. The first blank needs a past tense verb to describe how lectures were organized. "DIVIDE" becomes "divided".
2. The second blank needs an adjective to describe the libraries. "BIG" becomes "biggest".
3. The third blank needs an adjective to describe the collection. "ONE" becomes "one".
4. The fourth blank needs an adjective to describe the number of subjects. "IMPRESSIVE" becomes "impressive".
Answer: divided, biggest, one, impressive