a^,aˉ,a~\hat{a}, \bar{a}, \tilde{a}a^,aˉ,a~ a^,aˉ,a~\hat{\mathbf{a}}, \bar{\mathbf{a}}, \tilde{\mathbf{a}}a^,aˉ,a~ a^,aˉ,a~\mathbf{\hat{a}}, \mathbf{\bar{a}}, \mathbf{\tilde{a}}a^,aˉ,a~
$\hat{a}, \bar{a}, \tilde{a}$ $\hat{\mathbf{a}}, \bar{\mathbf{a}}, \tilde{\mathbf{a}}$ $\mathbf{\hat{a}}, \mathbf{\bar{a}}, \mathbf{\tilde{a}}$