Unit 7 Protect the Earth 习题1一、 句型转换。1. We should plant more trees to keep the air clean. （改为一般疑问句） we plant more trees to keep the air clean?2. You should turn off the lights to save energy. （改为一般疑问句） turn off the lights to save energy?3. You should cut more trees.（改为否定句） You more trees.4. We should use many plastic bags and plastic bottles.（改为否定句） We use many plastic bags and plastic bottles.5. We should save and reuse water.（改为疑问句） save and reuse water.二、根据课文内容填空。1. We drink water and water clean things every day.2. We save and rescue it.3. There is not much and on Earth.4. Wood from trees.5. We plastic make bottles and bags.