若${{a}_{0}}$、${{b}_{0}}$都是单位向量,则有( ).
${{a}_{0}}={{b}_{0}}$
${{a}_{0}}=-{{b}_{0}}$
$\left| {{a}_{0}} \right|=\left| {{b}_{0}} \right|$
${{a}_{0}}=\pm {{b}_{0}}$
∵${{a}_{0}}$、${{b}_{0}}$都是单位向量,
∴$\left| {{a}_{0}} \right|=\left| {{b}_{0}} \right|$,故$\text{C}$正确;
∵方向不确定,
∴$\text{A}$,$\text{B}$,$\text{D}$错误.
故选:$\text{C}$.