句型转换。
1. We should plant more trees to keep the air clean. （改为一般疑问句）
______ ______ 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.
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