“optional”的概念、定义、翻译、参考文献-科学参考

单词	optional
释义	optional 选购的任选的任意的任意选择的随意随意的可选择不是必需的
随便看	utility command utility consumption (水,电,汽) utility control console utility control facility(UCF) utility control facility (UCF) utility costs utility curve utility debug utility debugger utility design utility device list utility dolly utility facilities program (UFP) utility factor utility function utility generation utility glass ware utility glider utility graph utility index utility key utility lamp utility landing craft utility landing ship utility level

科学参考收录了1248194条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。