Problem: If "The sun was covered by a thick cloud all morning, but luckily, by the time the picnic started, it was gone.", is "The sun was gone." correct?

Answer: no

Problem: If "We went to the lake, because a shark had been seen at the ocean beach, so it was a safer place to swim.", is "The ocean beach was a safer place to swim." correct?

Answer: no

Problem: If "By rolling over in her upper berth, Tatyana could look over the edge of it and see her mother plainly. How very small and straight and rigid she lay in the bunk below! Her eyes were closed, but Tatyana doubted if she slept.", is "Tatyana doubted if Tatyana slept." correct?

Answer:
no