optional

英 [ˈɒpʃənl]

美 [ˈɑːpʃənl]

adj.  可选择的; 选修的

高考CET4CET6考研TOEFLIELTSGRETEM4TEM8化学

Collins.1 / BNC.5815 / COCA.5692

牛津词典

adj.

• 可选择的；选修的
  that you can choose to do or have if you want to
  1. Certain courses are compulsory, others are optional.
     某些课程是必修的，其他是选修的。
  2. This model comes with a number of optional extras (= things you can choose to have but which you will have to pay extra for) .
     这一型号有一系列可供选择的附件，价格另计。

柯林斯词典

• ADJ 可选择的；非强制的
  If something isoptional, you can choose whether or not you do it or have it.
  1. A holiday isn't an optional extra. In this stressful, frantic world it's a must...
     休假并非可有可无。在这个紧张而忙碌的世界，它是必不可少的。
  2. Sex education is a sensitive area for some parents, and thus it should remain optional.
     性教育对某些家长而言是个敏感领域，因此应该保持其非强制性。

英英释义

adj

• possible but not necessary

双语例句

• The mistake is to consider this as an "optional" activity.
  将其考虑为“可选的”活动就错了。
• Chinese is our optional course to us students of science.
  中文是我们这些理科学生的选修科目。
• The SOAP specification describes that a SOAP envelope can contain an optional header part.
  SOAP规范描述了SOAP信封可以包括一个可选的消息头部分。
• The second and third arguments are optional.
  第二和第三个参数是可选的。
• The next block defines the concept f: product, specifying a preferred label as well as optional alternates.
  下一个代码块定义了概念f：product，指定了需要的标签和可选的选项。
• We also recommend a full day optional excursion to the Upper Douro
  我们还推荐去杜罗河上游的短途自选一日游。
• Each can have zero or more parts, and each part can have a name and an optional type.
  每一个可以没有任何部分，或者有多个部分，每个部分都有一个名字和可选的类型。
• Note that both the dependencies and the instructions are optional; only the target and the colon are required.
  请注意依赖性和指令都是可选的；只有目标和冒号才是必须的。
• An activity can also have optional and required inputs and attributes, as defined by the activity's creator.
  活动还可以拥有可选和必要输入和属性，这由活动创建者定义。
• This contains a list of mandatory and optional fields.
  它包含一个强制性和非强制性命令的列表。