facultative

详细解释:a. 授权的, 机能上的, 才能上的, 能力上的, 兼性的, 可选择的, 任意的
【化】 兼性的

词型变化：

副词:facultatively

英语解释：

形容词 facultative:

of or relating to the mental facultiesable to exist under more than one set of conditionsgranting a privilege or permission or power to do or not do somethingnot compulsory

例句：

The last questions in the examination were facultative.最後的那些考题答兴不答可听自便。