In many countries, winter is from December to February. Autumn is 3 months before winter. In the autumn, leaves drop to the ground. Many trees have nuts or fruits. Animals may begin to store food. Some birds collect nuts to store. Other birds fly to a warmer place for the winter. They won't return until the spring. Days become shorter. Cold weather is coming. The fur of many animals gets thick because they need a thick coat to protect themselves. People also wear warmer clothes, because the weather is a little colder. In some places there may be rain or even snow, but in many southern places it is still warm. Autumn is also the time when farmers harvest their crops. People look forward to( 盼望) autumn for many reasons. The most important one is that autumn is the harvest season.

某沿海地区1999年以来酸雨频率明显增加，其原因可能是该地区（    ）

开心果耐旱怕涝。在西亚伊朗，品质最好的开心果产自环境恶劣的高原沙漠地区。这种现象表明(　　)