My last answer was deleted for being pointless, but I had to add more letters for the correct, succinct answer to be published. The right answer is "a sentence".
Answer:
Should
Explanation:
Should, it makes more sense to use the word "should not" instead of "must not".
Three They are all pretty un-important to the rest of the story. Why didn't you just google this?
Answer: The cherubin were angels, and in Macbeth's simile the couriers were not blind but invisible horses evidently coming to exact revenge for the murder. The word "horsed" shows that the "sightless couriers" are invisible horses.
Explanation: