PM2.5是指大气中直径小于或等于2.5×10^﹣3毫米的颗粒物，也称为可入肺颗粒物，把2.5×10^﹣3用小数形式表示正确的是（　　）

下列四图属于北半球的是（　　）

下图是某“家庭农场”的农业生产模式中食物网模式简图，请据图回答下列问题。

阅读短文，判断句子“正确”还是“错误”。

    Lily and Lucy are twins. They come from America. They came to China in 2004 because their parents came to China to work. Their father is an engineer, and their mother is a teacher. Lily and Lucy are 12 years old. They are in Grade 5, but they are in different classes. Lily is in Class 1 and Lucy is in Class 3. They walk to school every day. They have many friends in China. The girls and their friends often play together. They like hiking with their friends in summer and making snowmen with them in winter. They enjoy their life in China.

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