instruction:
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.
question:
I came upon this letter when reading a book, I couldn't find its name on the internet, you can imagine how hard it is to search about it. What is the name of the letter that follows 'sample space'? I know it's not really an English question, but I think this site is best fit for the question than say, the mathematics site.
answer:
It's an S written in a fraktur font used by mathematicians. This one is easy to find out using Detexify.


question:
For example, a man's name is Jeff Smith. My question is: When should I call him 'Jeff'? When should I call him 'Smith'? When should I call him 'Jeff Smith'? in western.
answer:
In general US usage, you would use 'Jeff' if you are friends, contemporaries, or Jeff has asked you to use his first name. First names are often used in casual settings. You would use 'Mr. Smith' (or 'Dr. Smith' or other appropriate title) if you are colleagues, younger than Mr. Smith, or in a formal or business setting. You would use 'Smith' in a very casual setting, particularly when playing sports. You would use 'Jeff Smith' when making an introduction, or if you needed to distinguish him from other Jeffs or Smiths, or sometimes when greeting him.


question:
In the book I am reading (Patrick Fairbairn, The Interpretation of Prophecy, 2nd ed., 1865), the abbreviation 'sq.' is used sometimes in referencing both Scripture and other books (as 'Typology of Scripture, vol. i. p. 100 sq.' or 'Ezek xxvi. 7, sq.'). What does 'sq.' mean in this context? (Instances of this abbreviation's usage may be found at Google Books here.).
answer:

Sq. is short for the Latin word sequiturque, which means the following. So p. 100 sq. means page 100 and those following pages. Here's the source.


