| 单词 | optional |
| 例句 | optional adjective •in senior year, phys ed is optional:voluntary, discretionary, not required, elective, noncompulsory, nonmandatory | Law permissive | rare discretional. ANT compulsory, mandatory, required. |
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英语同义词词典收录了14896条英语词条，基本涵盖了全部常用同义词或反义词的辨析及翻译，是英语学习的有利工具。