任选的 meaning in English

arbitrary
optional

Logarithms are defined with respect to an arbitrarily chosen constant .
对数是相对于一个任选的常数来确定的。
Optional subscription - time selectable service
任选的预约时可选业务
This is an optional feature
这是可以任选的功能部件。
These shall be carried out on poles selected at random by the purchaser or the engineer at the minimum rate 3 pieces of poles manufactured
这些测试将在由购买者或工程师在生产出的点中任选的三个以上点中进行