optional

形容词

1. 1

   可选择的、非强制的、自由决定的

   Attendance at the morning meeting is optional for part-time staff.

   兼职员工可自行决定是否出席晨会。

2. 2

   选修的教育

   She took two optional courses in film history this semester.

   她这学期选修了两门电影史的课。

3. 3

   选配的、额外加购的

   Leather seats and a sunroof are optional on this model.

   这款车的真皮座椅和天窗属于选配。