当下，人们对“舌尖上的安全”越来越关心，认为吃得健康比什么都划算，这说明，人们在践行（  ）

 在下列动物中，质量可能是3kg的是（　　）

    Mary is an American girl. She is now in Beijing with her parents. Mary doesn't know much Chinese, but she is studying it. She often speaks Chinese with her Chinese friends. Sometimes they can't understand her, because she can't speak Chinese very well.

    It's Saturday morning. She goes out. She is walking in the street. She wants to go to the zoo to see the elephants and monkeys, but she doesn't know how to get there. She asks a Chinese boy the way. The boy can't understand her. Then she takes out a pen and a piece of paper. She draws an elephant on it, and shows the picture to the boy. The boy understands, and shows her the way to the zoo.

我国面积最大的湖泊是（ ）

化学方程式是世界通用的化学语言，正确的化学方程式是（  ）