Answer:
Yes
Explanation:
The vague pronoun is "he". "He" could refer to his brother or John.
The thirteenth amendment states that slavery is abolished all throughout the United States. So A is the answer.
It depends on how you worded your essay and what your views on global warming are, the way I would word it is "in conclusion global warming is real and changing drastically every minute, and we don't fully know exactly how it will affect the world long-term" that's one way you can say it.
The indefinite pronoun neither is always singular.
Neither is the negative counterpart of 'either' which is also singular. The basic principle of Subject-Verb Agreement says that the subject and verb must agree with each other, so you should use a singular verb because 'either' and 'neither' are considered singular; however, this principle is sometimes broken by a plural verb which can be used after 'either' and 'neither' informally.