Given the Question and Answer pair, detect whether the answer is acceptable or not. Denote acceptable answer as "yes", otherwise denote as "no". An acceptable answer is consistent with the context in question, detailed, long, and uses general knowledge of English. Answers that are not definite and suggest a variety of options are not acceptable answers.

Example Input: Question: As an adverb, what is the difference between forward and forwards? 
Answer: The OED says this The present distinction in usage between forward and forwards is that the latter expresses a definite direction viewed in contrast with other directions. In some contexts either form may be used without perceptible difference of meaning; the following are examples in which only one of them can now be used: 'The ratchet-wheel can move only forwards'; 'the right side of the paper has the maker's name reading forwards'; 'if you move at all it must be forwards'; 'my companion has gone forward'; 'to bring a matter forward'; 'from this time forward'. The usage of earlier periods, and of modern dialects, varies greatly from that of mod. standard English. In U.S. forward is now generally used, to the exclusion of forwards, which was stigmatized by Webster (1832) as 'a corruption'.
Example Output: yes

Example Input: Question: I'm a non-native English speaker, and my automatic spellchecker seems to accept both therefore and therefor. Is one orthography preferred ? Is that a British vs. American difference ? Or an old vs. more recent orthography ? Or something else ? 
Answer: Therefore and therefor are completely different words. Therefor, an archaic word, means "for this", "for that", or "for it". E.g; ... ordering goods and enclosing payment therefor. Therefore means "for that reason" or "hence".E.g; Those people have their umbrellas up: therefore, it must be raining.
Example Output: no

Example Input: Question: I often hear US citizens say something like this: <Some phrases>. Period. What does period mean when it appears in a sentence by itself in this type of situation? 
Answer: A period is what the full stop is called in American English. Saying period at the end of a sentence is a way of expressing the finality of what is being said. For example, A: But phones are good for taking pictures. B: No, I don't think so. Phones should only be used for communication, period.
Example Output:
yes