voluntary

a.自愿的，志愿的

vol-au-vent, volatile, volatility, volcanic, volcano, vole, volition, volitional, volley, volley-ball, volleyball, volt, voltage, volte-face, volubility, voluble, volubly, volume, voluminous, voluntarily, volunteer, voluptuous, Volvo, vomit, voracious, voracity, votary, vote, vote down, vote in, vote through, voter, voting, votive, vouch, voucher, vouchsafe, vow, vowel, vox populi,