prep. 跨在...上

ad. 两腿分开着

[ adv ]
with one leg on each side
<adv.all>
she sat astride the chair

Astraddle \A*strad"dle\, adv. [Pref. a- + straddle.]
In a straddling position; astride; bestriding; as, to sit
astraddle a horse.