The mechanical pencil, patented in 1877, consists of a cylindrical piece of pencil lead inserted into a metal or plastic barrel against a movable rod that can be adjusted by a screwing motion to expose part of the lead.
- mechanical pencil [miˈkænikəl - ˈpensl] n. 自动铅笔
- patent [ˈpeitənt] v. 获得专利
- cylindrical [siˈlindrik(ə)l] adj.圆柱的
- plastic barrel [ˈplɑ:stik - ˈbærəl] n. 塑料管
- rod [rɔd] n. 杆
- screw [skru:] v. 拧，转
- expose [iksˈpəuz] v. 使暴露，使露出
