come across 偶然发现；偶然遇见，碰见；被理解
(教材原句P17)When you open a dictionary，you often come across a lot of unfamiliar words.
当你打开词典，你经常碰见许多不熟悉的单词。
[例] I absentmindedly turned the pages of the phone book and came across a city map.
我无意中翻开电话簿的一页，偶然发现了一张城市地图。
[知识拓展]
come about 发生
come out 出版；出来
come to 来到；合计，总共是；苏醒过来
come on (表示知道某人所说的话不正确)得了吧
come to an end 结束
come up with 赶上；提出
come from 来自
come into being 形成；产生
[即学即练] 用come的相关短语填空
①—You know what? I've got a New Year concert ticket.
—Oh，come on．You're kidding.
②Should you come across waste paper thrown out of a passing car，pick it up.
③Our students come from different backgrounds but have the same desire to learn online.
④I was amazed that he'd come up with this sweet idea.
