1. Usher invites the narrator for a visit.
2. The narrator encounters the Usher family physician.
3. Usher explains that his sister is dying.
4. Usher and the narrator spend their days reading.
5. Usher and the narrator take the coffin to the vault.
6. Both Usher and the narrator have difficulty sleeping.
7. The house of Usher is destroyed.
Answer:Breakthrough means a sudden dramatic, and important discovery or development.
Explanation: Its in a dictionary, if you have one!
'Apace' basically means with great speed, rapid movement, etc. Since you didn't include the passage, it's up to you to apply the definition in the context given.
Hopefully, this helps! =)
E? If there’s only one letter in it than it’s the letter u stated