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:
Possible Duplicate: Is a company always plural, or are small companies singular? When I'm referring to a group of multiple things, should it be considered singular or plural for the purposes of applying a verb to it? For example, which is correct in the examples below? A sentence is a group of words that is followed by a period. A sentence is a group of words that are followed by a period. The group of people constitutes a jury. The group of people constitute a jury. A group of crows is called a 'murder'. A group of crows are called a 'murder'. My instinct is that it depends on whether the verb is referncing the group itself or the members of the group directly, but is that right?.

Ex Output:
According to the OALD, group can actually serve as either a plural or singular noun. The category they give is 'countable + singular or plural verb'. So, an example of correct use is: A group of us is/are going to the theatre this evening. For any of your examples, both is and are can be used. I think the difference between them is as you say: use is when you are referring to the group, and use are when you are referring to the members of a given group. This page on when to use 'group' as plural from Washington State University backs this up, saying: When the group is being considered as a whole, it can be treated as a single entity: 'the group was ready to go on stage.' But when the individuality of its members is being emphasized, 'group' is plural: 'the group were in disagreement about where to go for dinner.' To analyze your given examples, here are some notes: A sentence is a group of words that is followed by a period. Use this form if you're talking about the group itself. That is, a sentence is a group of words followed by a period. A sentence is a group of words that are followed by a period. This implies that 'This. Is. A. Sentence' is a sentence. The group of people constitutes a jury. The group of people constitute a jury. This would be more correct, since you are describing the nature of the group. A group of crows is called a 'murder'. This would be correct, since you're again describing an entire group. A group of crows are called a 'murder'.

Ex Input:
For example, let's say I'm copying instructions by hand. The original instructions say: Multiply the first by the second Integrate the third with the fourth Integrate the third with the fifth And on a page I write: Multiply the first by the second Integrate the third with the fourth '' with the fifth I know this example is silly, but hopefully it's clear what I mean. What is this called?.

Ex Output:
They are ditto marks. ditto stems from the Tuscan dialect of the Italian detto - 'said'; Latin dictus - 'said'. Oxford Dictionaries Online.

Ex Input:
How do you know when to use singular or plural nouns if they're used as adjectives? i.e. 32-bit computer vs 32-bits computer? teacher union vs teachers union? wedding planner vs weddings planner? sport medicine vs sports medicine? student council vs students council? Which one is correct?.

Ex Output:
You are thinking of noun adjuncts, or attributive nouns. Both Wikipedia and someone from Pearson Education state that traditionally, all attributive nouns are singular. However, the number of plural attributive nouns have increased over the years in a rather arbitrary manner. This means that there is no longer a set rule to determine whether the attributive is singular or plural. Despite this, there is a rough guide that you can use. The attributive noun tends to be plural in the following situations: 1: The singular form might lead to ambiguity an arts degree (a degree in the humanities) as opposed to an art degree (a degree in fine art) [I believe that this situation is what is referred to on wikipedia as 'lexical restrictions', providing the example of 'arm race' vs 'arms race'] 2. There is no singular form of a noun (in pluralia tantum) a customs officer 3. There is a need to denote variety a soft drinks manufacturer [but] a car manufacturer 4. A topical issue comes forth, often in newspaper stories... the tapes issue the tapes compromise the Watergate tapes affair the White House tapes mystery and other examples, including jobs cut. [I am not entirely sure what the point of this fourth category is] [Source: Pearson Education , directly quoted apart from what is enclosed inside square brackets] To this list I add my own: 5. [The attributive noun is plural if] it comes from the possessive form of the word teachers union ladies man However, this is more of an explanation rather than a rule you can use. There are too many exceptions, and you are unlikely to know the origins of the word. It doesn't make sense that it is teachers union but not students council. Note that we often 'choose by ear and it doesn't matter (employee lounge, employees lounge)' (Chicago Manual of Style). I would argue that it would be easier to just look it up every time and memorise words instead of trying to find a rule or categorise them. Even as a native speaker, I was not entirely sure whether it was 'sport medicine' or 'sports medicine' before looking it up. If you find yourself completely lost and without internet, go with the singular form because it is the traditional form and more common.