下列图形中是旋转对称图形的有（ ）
①正三角形 ②正方形 ③三角形 ④圆 ⑤线段．
A：5个
B：4个
C：3个
D：2个
2013年8月31日，四川甘孜藏族自治州得荣县和云南迪庆藏族自治州德钦县、香格里拉县交界地区发生5.9级地震，同一天，上海宝山区丰翔路一冷库发生液氨泄露事件。无论是在地震还是液氨泄露事件中，党中央、国务院都把抢救人的生命放在第一位。这（ ）
①是因为每个人的生命只有一次，生命是宝贵的，也是脆弱的 ②启示人们应珍爱生命、善待生命
③表明任何时候都不能牺牲自己的生命 ④体现了人高于自然的理念
照样子填空
①写出表示手的不同动作的词。例：举 ____ ____ ____ ____
②写出表示不同的“看”的词。例：注（视） ____察 ____望 仰____
Dear students,
An English lecture will be held in the lecture hall from 4 to 6 p.m. On March 7. It will be given by Professor Li Ping from Peking University. The topic is “How to learn English well”. You may take notes if you like. And you may ask questions about learning English during the break. If you are interested, please attend the lecture on time.
English Club
March 2, 2017
Dear all students,
March 12 is Tree Planting Day. We have decided to go and plant trees that day. All the students in our school are supposed to take part in this activity. We are going to gather at the school gate at 7:00 tomorrow morning. And then, we will take our school bus to West Hill. Please don't be late or absent. Pay attention to safety during the planting. Please wear sports shoes as well.
Student Union
March 11, 2017
Found
A jacket was found on the playground on the afternoon of March 1. It is a new black jacket. There is a key in the pocket. The owner can come to Room 201, Building 3 to get it.
Li Hua
Class 3, Grade 8
①这是为什么呢？
②我们的工作、学习和娱乐越来越依赖电子设备，但是长时间盯着屏幕常常让我们感到眼睛疲劳
③另外，用电子产品的时候，我们与屏幕的距离和角度也经常变化，会迫使眼睛加倍努力去聚焦。
④所以，长时间盯着屏幕会使眼睛疲劳。
⑤因为注视屏幕的时候，屏幕的强光、闪烁、颜色和亮度会迫使眼部肌肉更加努力伸缩，以保持视线清晰。
已知（1﹣m2﹣n2）（m2+n2）=﹣6，则m2+n2的值是（ ）
