形容词
中文翻译：选择性的
同义词：
['optional', 'discretionary例句：1. The teacher gave us the option to choose our own textbooks.（老师给了我们选择自己教科书的选择权。）']
例句：
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1. The teacher gave us the option to choose our own textbooks.
老师给了我们选择自己教科书的选择权。
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2.The student decided to take an elective course in history.
学生决定选修一门历史选修课。
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3.The exam is optional; you can choose to take it or not.
考试是可选的，你可以选择参加或不参加。