1. Given $x, y, z$ satisfy $\frac{2}{x}=\frac{3}{y-z}=\frac{5}{z+x}$. Then the value of $\frac{5 x-y}{y+2 z}$ is ( ).
(A) 1
(B) $\frac{1}{3}$
(C) $-\frac{1}{3}$
(D) $\frac{1}{2}$
-、1.B.
From $\frac{2}{x}=\frac{3}{y-z}=\frac{5}{z+x}$, we get $y=3x, z=\frac{3}{2}x$. Therefore, $\frac{5x-y}{y+2z}=\frac{5x-3x}{3x+3x}=\frac{1}{3}$. Note: This problem can also be solved using the method of special values.