Part 1-
"Did you understand even a single word?" the attorney asked the parents.
The attorney spoke this statement because Gregor lost the ability to be able to speak their language, or any language. It puts Gregor farther away from humanity.
Part 2-
"In contrast, the fresh foods didn't taste good to him; he couldn't endure the smell and dragged the things that he wanted to eat a bit further away."
Gregor has already become an insect for he does not like human food and likes trash and rotten food more. This shows his alienation to the human life becoming stronger and stronger.
Part 3-
Then, apart from his will, his head sank down completely, and his last breath streamed weakly out of his nostrils.