| 例句 |
optionaladjective subject to one's freedom of choiceat the resort all recreational activities are optional, and you may choose to participate in none of them discretionary, elective, voluntary alternate, alternative, chosendispensable, unnecessary, unneeded, unwanted compulsory, mandatory, nonelective, nonvoluntary, obligatory, required essential, indispensable, necessary, requisite in 1765 |