有关南极地区的叙述,正确的是 （   ）
①有“高原大陆”之称       ②储存着大量的固体淡水资源      ③极端恶劣的气候条件，使得南极地区生物资源相当贫乏      ④ll月至次年3月，是去南极科学考察的最佳季节

B

    We are learning English, but how can we learn English well? A student can know a lot about English, but maybe he can't speak English.

If you want to know how to swim, you must get into the river. And if you want to be a football player, you must play football.

    So you can learn English only by using it. You must listen to your teacher in class. You must read English every day. You must speak English to your classmates and you must also write something in English sometimes. Then one day, you may find your English very good.

浙江某地乌鸫连续10年的种群数量增长情况如图所示，后一年的种群数量是前一年的λ倍，下列分析正确的是