①将图中的集气瓶分为5等份，并作好标记．

②在带橡皮塞和导管的燃烧匙内装入足量的红磷，将导管上的止水夹夹紧，在酒精灯上点燃红磷，并立即伸入集气瓶内，塞紧橡皮塞．

③充分反应后，待集气瓶冷却至室温，打开止水夹．

请回答下列问题：

    A shark(鲨鱼)sees a monkey. It says, “Hello, my friend, would you please come to my house? My mother and the others of my family want to see you.”

    “That's very good.” the monkey says, “But I can't swim.”

    “Oh, sit on my back. I'll take you there.” On the way, the shark says, “I must tell you my mother is ill, she wants to eat your heart.”

    “But I'm sorry, I don't bring it with me. I put it in the tree. Take me back and get it.” says the monkey.

    “Let's go back.” shark says.

    When they return, the monkey climbs up the tree and leaves the shark waiting for him in the water.

The watch ____ ____ ____China.

在经纬网中有两条经线和一条纬线是不用标注东西经或者南北纬它们是（    ）

①0°经线   ②0°纬线   ③180°经线  ④20°经线．