如图（5）所示的观察装置类似于光学中学过的(    )

下列反应属于置换反应的是（　　）

某生物小组的同学在玻璃温室内进行植物栽培实验，为此他们对室内空气中的二氧化碳含量进行24小时测定，下图曲线能正确表示其测定结果的是（横坐标为日时间，纵坐标为二氧化碳浓度）（  ）

    Do you know about Xiong'an? It's a new city near Baoding. There is a big lake in Xiong'an. Yes, it is Baiyangdian Lake. It is very big. In summer, you will see many beautiful lotus flowers on the lake. Some are red. Some are pink. Many people like them. There will be many boats on the lake. And there will be many birds singing in the grass. Xiong'an is beautiful and new. You can come here by bus from Baoding. And you can come here by train. You will play in the water with your friends. You will eat delicious fish. You will take many wonderful pictures. You will have a nice trip in Xiong'an.