计算（﹣2x²y）²的结果是（　　）

浙江省山地丘陵广布，适宜茶树的生长，但春季易受霜冻天气影响。为此，当地茶园引进了“防霜冻风扇”（如图）。当夜晚温度降到4℃时，风扇会自动打开，从而减轻霜冻对茶树的伤害。下图“为茶园某时气温垂直分布示意图”，关于风扇的作用原理正确的是（   ）

①风扇可以把高处的暖空气往下吹到茶树上

②风扇吹出的热风可以使茶树免受霜冻影响

③风扇的转动可以增强近地面对流运动程度

④风扇转动可带动空气流动，阻止上层冷空气下压

短文改错。

Our school held an English speech contest each year. Han Meimei won the first prize in last year. Everyone was sure that she was going to the champion again this year. Yet, to our surprise, she, instead getting the first prize, coming out second in the end. When the judge at the contest announced the results, Han Meimei felt so sadly that she almost cried. Therefore, she was not discouraged. When the second prize was given to her, she said to her, “The prize is not of important. I am going to work still hard to improve my English speaking ability.

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