在美国，学生课本重复使用，一本教科书平均寿命五年；在韩国，一次性台布、洗刷用品早已没有踪影；在日本，发明了一次性筷子，但严禁砍伐本国树木做筷子。这给我们的启示是（    ）

①必须节约资源                                  ②必须发展生产力

③必须实施可持续发展战略              ④坚持对外开放

阅读下列材料，按要求完成各题。

    This is Mr. Wilson's room. It's clean and tidy. It looks like（像） a nice picture. The walls are white and the window is big. You can see a photo of his family and a photo of his girlfriend on the wall. His girlfriend is Peggy Carmen. A yellow desk is near the window. You can see some green plants and five colorful flowers on it. A blue clock is on it, too. It is seven now. A baseball is under his bed. His T-shirt and his bag are on the bed. Look! What's that in the drawer(抽屉) of the desk? Oh, it's Mimi, a cat. It's black. It looks like a hat.

Ting-ting! Can you hear a ship? No. I can hear         .