Assignment3-the concordance tools of Large and Big

Question: Is there any rule governing the use of "big" and "large"? If yes, what is it? Use evidences to explain the major difference between the two words. Please limit your answer to 70 words.

Answer:
Most of the time "Big" and "large" are simliar in use. Even the native speaker can't really tell the difference between them.
After checking the concordance tools, I found that "large" is often used to describe the abstract amount, quantity and is also used with a phrases like a large number of , a large amount of , a large part of ....and so on.
On the other hand, "big" is often used to depict the concrete object to say about the size of the object.
There is an other conclusion is "large" is often used in more official occation while "big" is in more casual situation.