如图，正方形ABCD的边长为2cm，△PMN是直角一块三角板（∠N=30°），PM＞2cm，PM与BC均在直线l上，开始时M点与B点重合，将三角板向右平行移动，直至M点与C点重合为止．设BM=xcm，三角板与正方形重叠部分的面积外ycm²．

下列结论：

①当0≤x≤$\frac{2}{3}\sqrt{3}$时，y与x之间的函数关系式为y=$\frac{\sqrt{3}}{2}$x；

②当$\frac{2}{3}\sqrt{3}$≤x≤2时，y与x之间的函数关系式为y=2x﹣$\frac{2}{3}\sqrt{3}$；

③当MN经过AB的中点时，y=$\frac{1}{2}\sqrt{3}$（cm²）；

④存在x的值，使y=$\frac{1}{2}$S_{正方形ABCD}（$\frac{1}{2}$S_{正方形ABCD}表示正方形ABCD的面积）．

其中正确的是 ____（写出所有正确结论的序号）．

    Many young people like playing football very much. In China we can often see children playing football on the playground. In China and England, people call British soccer football. They don't call it soccer.
    A British soccer ball is round. There are eleven players in a team. But an American football is not round. It's like an egg. They also have eleven players on the field in one team.
    American football is very popular（流行的）in the USA. Players can catch the ball with their hands. But in a British soccer team, only the goalkeeper（守门员）can pick up the ball with his hands.
    Playing ball games is good for you. It can make you happy and healthy.

为使交通有序，安全，高速公路设立了许多交通标志，以下二幅图是高速公路指示牌，下列说法中正确的是（   ）

提出“罢黜百家，独尊儒术”建议的思想家是（  ）

六（1）班举行校园安全知识抢答竞赛．答对1题得10分，答错1题倒扣5分．第一小组共抢到15题，得了120分，这个小组答对了（　　）题．