设集合 $A=\left\{y \mid y=2^{x}, x \in R\right\}, B=\left\{x \mid x^{2}-1<0\right\}$, 则 $A \cup B=(\quad)$


$A=\left\{y \mid y=2^{x}, x \in R\right\}=\{y|y\rangle 0\}$.

$B=\left\{x \mid x^{2}-1\langle 0\}=\{x \mid-1\langle x<1\}, \therefore A \cup B=\{x|x\rangle 0\} \cup\{x \mid-1\langle x<1\}=\{x|x\rangle-1\}\right.$, 故选 C.