A:负数
B:非负数
C:正数
D:非正数
如图中甲、乙、丙三条曲线分别表示食物中三种营养物质在消化道中的变化情况,甲表示哪种营养物质( )
I am Lily. I like Music and PE very much. But I don't like Maths. Lucy is my friend. She likes Maths and Music very much. But she doesn't like PE. We love to dance and sing after class. We are good friends.
下列各句中,标点符号使用正确的一项是( )
下面是猫和鼠的部分生命现象,请分析说明它们各属于生物的何种基本特征: