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.
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- 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
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谢谢分享！你很牛也很伟大！
Merry Christmas!
谢谢李笑来老师！
一把鼻涕一把泪。。。。阿
不说了~~~ 大爱！
lead n.铅笔芯
怎么下mp3？？？