TASK DEFINITION: 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.
PROBLEM: So basically, I know the name for both sides of a coin, yet not the coin itself. In other words, when you refer to a coin, you don't want to say 'this object with one side heads, and the other tails', you would want to say 'this coin'. What I want is a general term to refer to two ideas, that are the absolute opposite to each other. I can't really use the word 'concept', or 'idea', because such words are already assigned to the very concepts/ideas themselves.

SOLUTION: polar opposites: polar opposite (plural polar opposites): The complete opposite, opposite in every way. 'Polar opposites' might also refer to the scientific or technical definition of two things having exactly opposing or inverted polarity, sign, orientation, or some other property.

PROBLEM: It seems that exemption and exception have the same meaning. However, they seem to be used differently. When should we use one and not the other?.

SOLUTION: They do have similar meanings. They both refer to leaving out an item from a set. The difference is how they are left out. an exemption is left out of the set by an authority or man-made rule. For example, a tax exemption, is money you received but does not have to be counted as part of our income because the tax laws explicitly say it's OK to ignore (presumably with the law created for some economic incentive purpose). an exception has no such man-made connotations (i.e. an exemption might be considered a kind of exception, but might be totally arbitrary). The number 2 is an exception to the idea that all prime numbers are odd (one would never use exemption in that context).

PROBLEM: Possible Duplicate: Do you use 'a' or 'an' before acronyms? I got the following sentence from the book I'm reading: You can take a database-first approach by first creating a SQL Server database schema. From what I learned, I think it should be 'an SQL Server database schema', not 'a SQL Server database schema'. So which one is correct?.

SOLUTION:
This depends, I would think, on your pronunciation of SQL. It can be pronounced as 'sequel', or spelled out as 'S-Q-L'. That perhaps doesn't help in written English. A thoroughly scientific survey of Google throws up many more hits for 'an SQL' than 'a SQL'. This is also the form used on that Wikipedia article and elsewhere, such as this Microsoft SQL Server documentation entitled 'Executing an SQL Query'.