下列有关说法正确的是（    ）

甲声音波形如图所示，把音调比甲高的乙声音输入同一设置的示波器，乙声音的波形是下列图中的哪一幅（　　）

从方框中选择适当的单词完成短文。

   What's this on the table? It is a ____  of my new classroom. ____  at the picture. ____  can you see ____  the classroom? I can see a ____  desk in the front of the classroom. Some books are ____  the desk. I can see two white ____ , too. There are____  colored chalks (彩色粉笔n them. ____  is the broom (扫帚)? It’s ____  the door. I like this new classroom.

下列关于长江概况描述正确的是