Wait... what was I going to say again? I often forget what I wanted to say when the teacher calls on me to speak. Can you make me a tool to solve this?

Requirements:


The program must loop as follows:


First, take in input
If the input is empty, print the last stored question.
Otherwise, store the input as a question.



Notes:


The input will never be empty if there are no questions stored. 


Clarification: The program does not need to store multiple questions. I originally wanted it to store multiple, but I changed it after many people misunderstood the question.

Remember, this is code-golf, so the code with the smallest number of bytes wins.
Perl, 13 17 14 +1 = 15 bytes
/./?$;=$_:say$

+1 for the -n flag
(saved 4 bytes thanks to @Dada)
As long as the input is not equal to the carriage return, it stores the input in $;.  If it is equal to the carriage return, it prints what's already in $;.
This assumes that all input can be characterized as questions, even if grammatically, they are not such.