Shanghai changes a lot in transportation(交通).

    In the past, there were few cars. Now there are many kinds of cars. There were not any bridges above the Huangpu River. Now there are some bridges on it. There were no tunnels(隧道)under it.

    There were no undergrounds. Now there are many undergrounds. There were no light rails(轻轨)and maglevs(磁悬浮). Now there are some lights and maglevs.

    The changes make our lives more convenient(方便). I like the changes.

If farmers _______ the land, the animals won't have any places to live in.

实验室有一瓶标签残缺并且瓶盖没有完全密封的无色溶液（如下图），化学小组的同学经过寻问老师后只知道是NaCl、NaOH、Na₂CO₃、NaHCO₃中的一种溶液，为确认原瓶中是何种溶质并判断其是否变质，化学小组的同学进行了如下的探究活动：

【进行猜想】

猜想I：原溶液的溶质是NaCl；

猜想II：原溶液的溶质是NaOH；

猜想III：原溶液的溶质是Na₂CO₃；

猜想IV：原溶液的溶质是NaHCO₃．