IFF

A midterm exam was done! Actually, I was so nervous because this is the first time I take a comprehensive test, not mathematical or mere English test. I studied a little yesterday. Fortunately, 80% of questions were the multiple question, so it is not hard for me to answer, but remaining was an essay type question that I had to describe the definition of a specific term with some examples as my answer.

Also, there was a new experience to me. I have never heard student had better bring their own answer sheet which is like a mark sheet. But, in the class I took the test, every students brought their own answer sheet to the class, so I did so as well.

Now, I'm studying for another exam. I found an expression which is...
"if and only if..."
The meaning is that there is possible only under the circumstance. I've never heard this expression before. I learn something new everyday...