1.The fog is not permanent it moves it stays only for a moment as in the last sentence it moves on.
2. D a metaphor it using the cat as a metaphor for the fog.
I'm not sure what the lesson is, but the answer that makes sense the most is number. Number because most lessons in subject-verb agreement concerns the singularity and plurality of the subject at hand
I would say the answer is "harbor". This word is usually used as a noun; but in this case, it is a verb that means to provide shelter to someone or something, to keep someone safe, but also to have something in mind and think about it. This word is purposefully chosen and fits into Whitman's well-intended, philanthropic and inclusive worldview.
