若 $A\left(x_{1}, y_{1}\right), B\left(x_{2}, y_{2}\right), C\left(x_{3}, y_{3}\right)$ 是反比例函数 $y=\frac{3}{x}$ 图象上的点, 且 $x_{1}<x_{2}<0<x_{3}$, 则 $y_{1} 、 y_{2} 、$ $y_{3}$ 的大小关系正确的是 ( )
$\because A\left(x_{1}, y_{1}\right), B\left(x_{2}, y_{2}\right), C\left(x_{3}, y_{3}\right)$ 是反比例函数 $y=\frac{3}{x}$ 图象上的点,

$\therefore x_{1} \cdot y_{1}=3, x_{2} \cdot y_{2}=3, x_{3} \cdot y_{3}=3$,

$\because x_{3}>0$,

$\therefore y_{3}>0$,

$\because x_{1}<x_{2}<0$,
$\therefore 0>y_{1}>y_{2}$,

$\therefore y_{3}>y_{1}>y_{2}$.

故选 $A$.