俗话说“大树底下好乘凉”、“千里之堤，溃于蚁穴”．这都体现了（  ）

阅读材料，回答问题

材料一：湖南省人民政府《关于加强农村留守儿童关爱保护工作的实施意见》中指出，公安部门要及时依法查处侵害未成年人权益的违法犯罪行为，对侵害未成年人案件，果断处置。加强校园安全管理和周边环境整治，指导督促中小学校、幼儿园完善人防、物防、技防措施，配合教育部门加强法治安全常识普及和预防校园暴力事件，依法严厉打击侵害未成年人的违法犯罪行为。

材料二：一天，小明遇到外校的高年级学生在西大街溜达，让他“赞助”点钱给他们去网吧，还拿随身携带的水果刀吓唬小明。小明见跑不掉又敌不过，就故意对他们说跟他回家取钱，便三转两转把他们带到了执勤交警面前……

   I am Bill Jones. I am a teacher of English. My wife is Linda Jones. She is a nurse. We have a daughter and a son. We have many friends.
Look! These are my friends. This is Mr. Black. He is a worker. He works in a shoe factory He makes shoes there. That’s Mrs. Black. She is a worker on a farm near here. The girl is their daughter. She is a student. She is thirteen. The boy is their son. He is a young soldier（战士）. His name is Carl Black.

下列式子中：①2＜0；②2x﹣3＞0；③x=2012；④x²﹣x；⑤x≠0；⑥x+3＞x+1，其中是不等式的有____（填序号）