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1·Certain courses are compulsory, others are optional.

某些课程是必修的，其他是选修的。《牛津词典》

2·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。《柯林斯英汉双解大词典》

3·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。《牛津词典》

4·Is that optional course as hard as everybody says?

那门选修课真像大家说的那么难吗？

5·You took an optional course this semester, didn't you?

你这学期选了一门选修课，是吗？

6·It is said that in England death is pressing, in Canada inevitable and in California optional.

据说，在英国死亡是迫在眉睫的，在加拿大死亡是不可避免的，在加州是可以选择的。

7·Other bath accessories, such as a loofah sponge, or bath gels, or potpourri, are very optional.

洗澡需要的其他东西，比如丝瓜络、沐浴液、精油都是可选的。

8·Schools in our city provide a variety of optional classes to cater to students of different levels.

我们市里的学校提供各式各样的选修课，以满足不同水平的学生。

9·In the new curriculum, some courses are compulsory, while others are optional for middle school students.

在新课程中，一些课程是必修课，而另一些是中学生的选修课。

10·By setting Peking Opera as an optional course, students may have more freedom to decide whether to take it or not.

通过将京剧设置为选修课，学生们可以有更多的自由决定是否选修京剧。

可选

1·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。《柯林斯英汉双解大词典》

2·We still have the problem of those optional parameters.

对于我们来说，那些可选参数仍然有问题。

3·But if the string is an address or optional field, you may have megabytes of zeroes on disk.

但如果字符串是一个地址或可选的字段，那么磁盘上可能会有成兆字节的零。

4·In this process, some of the variables are primary elements that are necessary for input, while others are optional.

在这一过程中，一些变量是基本的元素，是必须输入的，而其它一些却是可选的。

5·This completes the optional portion of this exercise.

这个练习的可选部分也完成了。

可选择

1·The label field in this extension is optional.

这个扩展中的标签域是可选择的。

2·Note that using model fragments is optional in the workflow of this scenario.

注意使用模型片段在该场景的工作流程中是可选择的。

3·The next page of the wizard ( Figure 12) is for entering optional caption values.

这个向导的下一页（ 图 12）描述的是输入可选择的标题名称。

4·Again, the return messages are an optional part of a sequence diagram.

此外，返回消息是序列图的一个可选择部分。

5·You may simply want to indicate that the fragment is optional.

你可能只是想要指出片段是可选择的。

随意的

1·We will not, however, treat this project as an extracurricular or optional activity.

但是，我们不会将这个项目当作业余的或随意的活动来对待。

2·Not optional. You'll be glad as the savings grows, and especially when emergencies come up.

不随意，你将很开心看到储蓄增长，特别是当紧急情况发生时。

3·On a three-button jacket, you button the middle; the top button is optional.

三个扣子的外套，你扣住中间的，顶上的随意。

4·So I filter all of them into a “Review Optional” folder – and if I have time, I’ll browse them at my leisure.

因此，我把这些邮件全都过滤到一个名为“随意查看”的文件夹，如果我闲得无聊，就打开来看看。

5·The modern house life is a kind of free style, a comfortable and warm feeling, also o kind optional beauty.

现代家居，应是一种自由的方式，一种舒适的温暖感觉，同时也是一种随意的美丽。

自选

1·The optional courses offered by out school enrich our knowledge and broaden our minds.

学校提供的自选课程丰富了我们的知识，也开阔了我们的视野。

2·Buy a hundred or whether thousands of products, all business is self-purchase, postage paid, and optional automatic modes of transport time, 24-hour self-help.

不论买一种百种或是千种商品，所有业务都是自助购买，自动计算邮费货款和自选运输方式运输时间，24小时自助。

3·Team pennant specification: in length 200 centimeters, in width 200 centimeters, color optional.

队旗规格：长200厘米以内，宽200厘米以内，颜色自选。

4·T he results show that the parameter of difficulty should be put into consideration during arranging the optional entire exercises, since it would affect the final score.

结果显示，自选成套动作的编排，应考虑到难度值计入成套最后得分这一因素 ；

5·We will have an informational meeting and registration for optional Tours at the hotel. Take your time for fitting the winter clothing (optional), shopping and dinner on your own.

我们要在酒店召开一次信息发布会，让大家登记自选的出游活动，还会留出充足的时间来让大家挑选合适的冬装(选件)、购物并自己享用晚餐。

可选择性的

1·Optional reading means, if they don't get read, there will be no significant consequences other than not benefitting from the information they contain.

可选择性阅读的概念是，如果你没有阅读这些文件，也没有什么重大的后果，不会因此就影响收益。

2·Transferability assures the efficiency and effectiveness of various facilities in the housing environments and optional accesses reflect the social equity and goals of realizing diverse demands.

通达性保障着居住环境各种功能使用的效率和效果，通达的可选择性体现了社会公平与实现多样需求的目标。

3·You can specify an optional dependency requirement that can be satisfied by a J2EE datasource capability using a dependency relationship link, as shown in Listing 18.

您还可以确定一个可选择性的从属需求，这个需求可以由一个J2EE数据源性能通过使用一个从属关系连接来实现，如清单18所示。

4·SNC will also charge Customer for the purchase of optional, added services offered by SNC.

SNC也将收取客户可选择性购买、由SNC提供的增值服务的费用。

5·We further propose an optional disassembly planning algorithm for mechanical parts based on disassembly waves.

并在此基础上提出了一种基于拆卸波的零件可选择性拆卸规划算法。

任选

1·An apple a paring knife or apple corer a melon baller or spoon (optional).

一个苹果、一把水果刀或苹果去心器、一个搓球机或勺子(任选)。

2·Sink and accessories free combination, high, medium and low grade optional, and offers a variety of packages, provides professional consulting services and custom.

水槽和配件自由组合，高、中、低档任选，并提供多种套餐，可提供专业咨询服务并可定制。

3·Of course, if some optional information is missing from the HTML document, the associate fields will be left blank, but this is not uncommon in any database.

当然，如果某些任选信息在HTML文档中缺失，有关字段就留作空白，但这种情况在任何数据库中都是常见的。

4·Degradation triggers can be temperature or chemical reactants, with optional accelerators or retarders to provide the desired timing for plug removal.

降解引发要素可以是温度或化学反应物，以及任选的加速剂或缓速剂以提供所需的封堵去除时间。

5·On the contrary a variety of optional components are described to illustrate the wide variety of possible embodiments of the present invention.

相反，说明许多任选部件以示出本发明的多种可能的实施例。

可选配

1·The standard battery is a 6-cell unit and an optional 8-cell battery is available providing 6:46 hours of run time with WLED display option.

标配六芯电池，并可选配8芯电池，电池续航能力为6：46小时。

2·Metal test frame, equipped with adjustable supporting feet, fabric installation clip and aluminum ashes plate. But will set a placed in optional on the balance of and digital readouts.

金属测试架，配有可调支脚，织物安装夹及铝制灰烬盘。可将套具放置在可选配的天平上并数字读数。

3·This model can upgrade, the helper HL-350 is optional, according to customer's demand.

可升级机型，根据用户需要可选配hl - 350型机械手。

4·Auto-adjust height of cutting gun and multiple torch clamp structure. Optional item: disassemble cutting table.

标配电动高度调节装置及万能割枪夹紧器。可选配拆装式切割工作台。

5·Moreover, positioning air cylinder is an optional part, easier and more accurate fof positioning.

另外可选配定位气缸，工件定位方便、准确。

可供选择

1·So the library books are all optional background.

所以图书馆内的书，都是可供选择的背景资料。

2·At last, the paper proposes four optional types for enterprise cultural construction.

最后，文章给出了四种可供选择的企业文化建设类型。

3·The similar complex situation possibly occurs in the separate dynamic system, based on Cellular Automata model for the research dynamic system behavior provided another optional method to be possible.

类似的复杂情况可能发生在离散动力系统中，基于元胞自动机的模型为研究动力系统行为提供了另一种可供选择的方法。

4·Without optional colors and shapes, the product will lack competitiveness.

没有多种颜色和形状可供选择，该产品缺乏竞争力。

5·The optional needle gauge has five specifications.

针间距有五种可供选择。

选装

1·Optional high flower is aspersed, sprinkler control pneumatic valve, 20 metres green reel, etc.

选装高位花洒、洒水控制气动总阀、20米绿化卷盘等。

2·The color sizing and additive join the mixing head directly, reduction of cost , increase of efficiency(optional parts).

色浆和添加剂直接进入混合头，降低成本，提高效率（选装部件）；

3·The utility model relates to an automobile tyre mudguard, belonging to optional automobile parts technical field.

本实用新型涉及一种汽车轮胎用的挡泥板，属于汽车选装零部件技术领域。

4·Reserved for remote monitoring, remote control module, the wind pipe interface module can be optional according to need.

预留远程监测、远程控制模块，风管接口模块，可根据需要选装。

(1)optional course选修课，选修课程

(1)optional parameter任选参数，可选参数

(1)optional exercise自选动作

(1)optional equipment【计】附加设备；任选设备

(1)optional item可选择项目