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- Declare which element may be a required or optional variable for the invocation. 指明哪一个元素是调用服务必须的或可选的变量。
- The insurance cover is optional. 保险范围可以随意选择。
- A 4-speed automatic transmission is optional. 四段自动变速器是可自由选择的。
- A constant, variable, function name, or expression. 一种常数、变量、函数名或表达式。
- The prices are variable, shop around by all means. 价格高低不一，所以一定要货比三家逐店选购。
- The temperature was a variable in the experiment. 在该实验中温度是个变量。
- An optional academic course or subject. 选修的科目选修课程或课题
- The cassette player is an optional extra in this make of car. 这种型号汽车如需盒式磁带唱机费用另计。
- A finite increment in a variable. 变量增量变量的有限增量
- The speed of the toy boat is variable. 玩具船的速度是可变的。
- Winds are mainly light and variable. 风力较弱，风向多变。
- You must do it; you have little option. 你必须做,你没有选择的余地。
- It is at your option to stay or leave. 去留随你的便。
- A programmed time delay of variable duration. 暂停，展宽一种由程序设置的可变持续时间的时间延迟
- You must do it; you have no option. 你必须做，你没有选择的余地。
- She has taken an option on that piece of land. 她已取得那块土地的购置权。
- Permitting discretion; optional. 允许自行处理的; 随意的
- The former option favours the married man. 前一种选择对已婚男子有利。
- optional variable 选择变量
- An estimator is a random variable. 估计量是一个随机变量。
