What is the difference between logical statements and statement variables? For the following two question
Let P, Q, and R be logical statements. Use a truth table to prove that_______.
Let P, Q, and R be statement variables, and suppose that the logical expression_______ is false.
The blank is two expressions which I don't know how to type those symbols, hope it doesn't matter.

Statement variables are atomic statements, i.e. statements with no connectives in them. Statement variables are usually written as letters $p, q, r, \ldots$.
Logical statements are any statements composed of statement variables and, possibly, connectives. For example: $p$, $\neg p$, $p \land q$, $(q \lor p) \to (r \lor q)$, $\ldots$.  
Every statement variable makes for a logical statement, but not every logical statement is a single statement variable.
