阅读理解

People communicate(沟通)in many different ways．The most common way is by talking with others．Besides talking，we can also use body language．When we use body language，we need to use body to show what we mean．Sign language is a kind of body language．Let’s see more about it．

  Sign language is popular among dumb people who are unable to speak or don’t want to speak．If you want to communicate with a foreigner，but you can’t speak his language and he can’t speak Chinese，what can you do?Maybe you can communicate by making signs．Now let’s learn some signs Indians often use．

    *When they are hungry，they move their right hands back and forth in front of their stomachs．

    *When they mean“Let’s eat”．they put their right hands and move them up and down in front of their mouths．

    *When they have had enough，they part their thumbs and first fingers,and move their hands from their chests to chins．

    *If they have a stomachache，they put both hands on their stomachs，and move them back and forth．

①y=f（x）的最大值为 $\sqrt{2}$ ；

②y=f（x）最小正周期是π；

③y=f（x）在区间 $\frac{\pi }{24},\frac{13\pi }{24}$ 上是减函数；

④将函数y= $\sqrt{2}$ cos2x的图象向右平移 $\frac{\pi }{24}$ 个单位后，将与已知函数的图象重合．

其中正确命题的序号是____．

I will never forget my first English class. It is very interesting. It's the first class in the morning. The teacher goes into the classroom with a smile on his face. At the beginning, he makes a self-introduction(自我介绍). And he tells us that his English name is John. Then he asks all of us to think of English names for ourselves. We are very excited(兴奋的) to find a good name. Then he asks us to write our names down on a piece of paper. I think about my English name for a long time. Then I come up with(想出) a beautiful name ---Shirley. All the students write their names down and give the paper to the teacher. When the teacher calls “Shirley” to answer his question, three girls stand up at the same time.