Generate the answer for a given question. The question requires common knowledge of English. Make sure that the answer is in detail, long, consistent with the context, and requires general knowledge of English. To be less repetitive, please vary your language for each question. Give a proper explanation to answer, and if necessary, provide the definition of various terms. And conclude your answer if it's long. If you have used other resources (e.g., Merriam Webster's.) to answer the question, include citations in your answer. You don't need to paraphrase the context of your resources, but make sure that your answer is consistent and complete.

Ex Input:
As generally agreed and as extensively discussed in this question, 'an' should be used in place of the more common 'a' where the following word begins with a vowel sound. I have just encountered for the first time an instance of the phrasing an mule in the book Why Chemical Reactions Happen (James Keeler and Peter Wothers, Oxford University Press, 2003). (This book is not mine. I was sitting opposite a friend when the friend mentioned the unusual phrasing.) This phrasing appears to contradict the rule discussed above, since 'mule' is, as far as I am aware, pronounced /mjul/ (see Wiktionary). Here is the context. The author is using an analogy to explain a chemistry concept (the italics are not mine, but the bold emphasis is): A useful analogy here is that of an mule, which we get by crossing a horse with a donkey. To describe an mule as a horse or a donkey would be inaccurate and it certainly does not interconvert rapidly between the two! Rather we need to recognize that although an mule has parts that are reminiscent of a horse and parts that a reminiscent of a donkey, it is something altogether different. Looking for other examples online, I have managed to find one on Wikipedia's List of Siege engines. Discussing a Siege engine, the Scorpio: Similar to the ballista, but smaller. Was sometimes mounted on an mule-drawn cart. Other examples are difficult to find, but here's one from a user-posted question on Answers.com (referring, notably, to a kind of deer rather than the animal, a mule): Is an mule deer an omnivore? No. Mule deer are herbivores. ... What is going on? Is there an irregular pronunication of 'mule' of which I am not aware? Is this some strange language quirk, some archaic spelling that I am encountering for the first time?.

Ex Output:
The original printing had 'an ass' instead of 'an mule'. That error was not lost on the chemistry community. See, for instance, Krenos's 2004 review of the text in the Journal of Chemical Education: In Chapter 10, bonding in extended conjugated systems and resonance are introduced with the horse + donkey = ass analogy (it is likely the hybrid animal mule is intended instead of ass, however). It seems the editors subsequently made an error mistake.


Ex Input:
Why is the verb when paying for a service subscribe, but the noun form is subscription? Is there a rule that changes 'b' to 'p'?.

Ex Output:
The 'rule' goes right back to Latin (and probably to pre-Latin) where suffixes starting with an unvoiced consonant, such as '-tu' (earlier '-to') and '-si' caused a final voiced consonant on the root to be devoiced. Examples: scrib-o 'I write' -> scrip-si 'I have written', scrip-tum 'written' dirig-o 'I steer' -> direxi (direk-si) 'I have steered', direc-tum 'steered' So you see there are other similar pairs in English (eg 'dirigible' and 'direct' - though 'dirigible' is not a very common word, it's true) Unfortunately, rules like this that go all the way back to Latin, are not very useful to learners of English, because they don't always apply to every case that might appear similar. So although most English words that end in '-ibe' are derived from 'scribo', and have nouns in '-iption' (subscription, inscription, description, ascription), 'imbibe' is an exception: There is no noun '*imbiption'. And conversely, there are nouns in '-ruption' (disruption, corruption, interruption) but their corresponding verbs end in '-rupt', not '-rube' as you might have guessed.


Ex Input:
I would like to use a noun made of multiple words (like particle board, Mount Everest, or windscreen wiper) in a compound adjective with a hyphen. But I don't know how to hyphenate such a composition. I'm not sure how common this situation is, so here's an example: Machine learning is a single noun made of two words, and I want to use it in a compound adjective with a hyphen. Are either of the following examples correct? I would like to pursue a machine learning-related certification. I would like to pursue a machine-learning-related certification. If not, then what is the correct way to hyphenate compound adjectives like this?.

Ex Output:

Bryan Garner, Garner's Modern American Usage (2003) has a useful discussion of this problem in his lengthy coverage of phrasal adjectives: E. The Compound Conundrum. When the first or last element in a phrasal adjective is part of a compound noun, it too needs to be hyphenated: post-cold-war norms, not post-cold war norms. Otherwise, as in that example, cold appears more closely related to post than to war. In your example, machine learning is the compound noun and related is the additional element in the adjective phrase, so Garner would endorse punctuating it as machine-learning-related. The Chicago Manual of Style, fifteenth edition (2003) takes essentially the same position as Garner: 5.92 Phrasal adjectives. A phrasal adjective (also called a compound modifier) is a phrase that functions as a unit to modify a noun. A phrasal adjective follows these basic rules: ... (2) If a compound noun is an element of a phrasal adjective, the entire compound noun must be hyphenated to clarify the relationship among the words {video-game-magazine dispute} {college-football-halftime controversy}. Words Into Type, third edition (1974) emphasizes the practical goal to be achieved by hyphenating (or not hyphenating): Phrases used as attributive adjectives usually require hyphenation to make clear their relation to the noun they modify. [Examples:] the how-to-study area; a life-and-death struggle If such a phrase modifier is hyphenated at all, it should be hyphenated throughout; but no hyphen should be used between the modifier and the noun. Wrong: low milk-and-cream yielding dam Right: low milk-and-cream-yielding dam Wrong: pay-as-you-go-plan Right: pay-as-you-go plan If there is scarcely any possibility of misreading, hyphens need not be used. [Examples:] a story and a half house; a thirty percent increase; yellow pine timber belt All of these (U.S.) style guides agree that when ambiguity as to what is modifying what might ensue from an unpunctuated adjective phrase, it is better to hyphenate the elements of the phrase than to leave the words open. But the goal is greater clarityand if the hyphens don't clarify anything, they have no business being there. Thus far, my answer has focused on the 'machine-learning-related certification' example in your question. Compound modifiers that incorporate proper nouns of two words or more (such as 'Mount Everestbased climbing expedition') follow a different rule in these style guides: leaving the proper name open, and connecting the compound noun to the adjective with an en-dash instead of a hyphen. I won't go back into the reference works to quote the specific guidelines from each book, but they recommend the approach I have just outlined in this paragraph.


