傍晚6点妈妈下班回家，你应该对她说：

若定义运算：a⊗b= $\{\begin{array}{c}a,\left(a\ge b\right)\\ b,\left(a<b\right)\end{array}$ ，例如2⊗3=3，则下列判断中错误的是____

①a⊗b=b⊗a；

②a⊗（b⊗c）=（a⊗b）⊗c；

③（a⊗b）²=a²⊗b²

④c•（a⊗b）=（c•a）⊗（c•b）（c＞0）

①如图连接仪器，向外拉注射器的活塞，一段时间后，松开手，注射器的活塞恢复至原位。

②在有孔燃烧匙上放置一小块(足量)白磷，塞紧橡胶塞，关闭K。

③向烧杯中倒入足量80℃的热水。

④打开K，将注射器的活塞向上拉到100mL处，观察现象。

⑤2分钟后，迅速将注射器的活塞推至底部，并立即关闭K，观察现象。

⑥……。

回答下列问题：

根据短文理解选择答案。

      The students start arriving on our playground from about 8:45 am. Most of our children walk but some travel to school by car.

      The children wear a school uniform and carry their homework and lunch in a school bag.

      School begins at 8:55 a.m. The duty teacher blows a whistle and the children line up in their class groups. They wait quietly for the teacher to send them to their classrooms.

      On arriving in their classrooms, the children empty their bags and put their homework in the marking boxes. The children then go back into their classrooms.

      The children do their early morning work while their class teacher takes the attendance register(考勤簿).The teacher reads out each child’s name in turn. At 9:10 a.m., the children go to assembly in our main hall. They sit on the floor in rows with the youngest children at the front and the older children at the back. As the children go into the hall, they listen quietly to the music playing.