Which of the following statements are always true?
(There may have multiple answers.)
If $A$, $B$ are two $m \times n$ matrix and $C$ is an $m \times m$ invertible matrix such that $CA = B$, then $A$, $B$ are row equivalent.
If $A$, $B$ are two $m \times n$ row equivalent matrix and $C$ is an $m \times m$ matrix such that $CA = B$, then $C$ is invertible.