1、Certain courses are compulsory, others are optional.───某些课程是必修的，其他是选修的。
2、The owner of each end point decides how much optional information to provide with the endpoint URL.───每个端点的所有者决定端点URL提供多少可选信息。
3、A few days before a big social-science exam, the instructor informed us that he would hold an optional review session the next day.───在一场大型社会科学考试前几天，导师通知我们第二天他将会给我们上一节选修复习课。
4、Optional extras include cooking classes at a top restaurant.───可选的额外之物包括一家高级餐馆的烹饪课程。
5、The new lock-in offer is part of a series of optional add-ons airlines have been rolling out in an effort to increase revenue.───这个全新的票价锁服务是其中一个航空公司为了增加盈利而推出的一系列附加服务选项。
6、In fact, for one-to-one associations that are optional on both end, the code generated by the wizard is all we need.───实际上，对于两端都可选的一对一关联，只需要向导生成的代码就够了。
7、The course consists of ten core modules and five optional modules.───这门课程包括十个必修单元和五个选修单元。
8、After a join hint is specified, the INNER keyword is no longer optional and must be explicitly stated for an INNER JOIN to be performed.───指定联接提示后，要执行INNERJOIN时，INNER关键字不再为可选，而必须显式说明。
9、In some smaller restaurants with fewer people dining, like the case of a couple of diners, the measure's adoption could be optional.───有一些小餐馆就餐人数比较少，比如一两个人、两三个人，可以有一些随意的情况。
optional（意思翻译）
adj.可选择的，随意的
optional（相似词语短语）
1、optionable───可选择的
2、ovational───欢呼的
3、optical───adj.光学的；眼睛的，视觉的
4、coitional───交谊的
5、emptional───空的
6、notional───adj.猜测的，想象的；表意的；（语言教学中）培养交际能力的；概念上的；抽象的
7、optionally───adv.随意地
8、National───n.（印、巴）耐提奥纳乐（人名）；adj.(national)国家的；国民的；民族的；国立的；n.(national)（某国的）公民
9、motional───adj.运动的；起动的
optional（双语使用场景）
1、Certain courses are compulsory, others are optional.───某些课程是必修的，其他是选修的。
2、The owner of each end point decides how much optional information to provide with the endpoint URL.───每个端点的所有者决定端点URL提供多少可选信息。
3、A few days before a big social-science exam, the instructor informed us that he would hold an optional review session the next day.───在一场大型社会科学考试前几天，导师通知我们第二天他将会给我们上一节选修复习课。
4、Optional extras include cooking classes at a top restaurant.───可选的额外之物包括一家高级餐馆的烹饪课程。
5、The new lock-in offer is part of a series of optional add-ons airlines have been rolling out in an effort to increase revenue.───这个全新的票价锁服务是其中一个航空公司为了增加盈利而推出的一系列附加服务选项。
6、In fact, for one-to-one associations that are optional on both end, the code generated by the wizard is all we need.───实际上，对于两端都可选的一对一关联，只需要向导生成的代码就够了。
7、The course consists of ten core modules and five optional modules.───这门课程包括十个必修单元和五个选修单元。
8、After a join hint is specified, the INNER keyword is no longer optional and must be explicitly stated for an INNER JOIN to be performed.───指定联接提示后，要执行INNERJOIN时，INNER关键字不再为可选，而必须显式说明。
9、In some smaller restaurants with fewer people dining, like the case of a couple of diners, the measure's adoption could be optional.───有一些小餐馆就餐人数比较少，比如一两个人、两三个人，可以有一些随意的情况。
optional（英语使用场景）
1、The goods are optional, but only one.