某生物兴趣小组为探究绿色植物的光合作用和呼吸作用，设计了如下实验装置，请分析作答：

①对于任意的x∈0，e，总有f（x）≥0；

②f（e）=e；

③若x₁≥0，x₂≥0，x₁+x₂≤e，则恒有f（x₁+x₂）≥f（x₁）+f（x₂）．

    This is my family．This is my father．He is strong．He has short hair．He is a doctor．This is my mother．She is not fat．She is a nurse．She has long hair．This is my grandfather．He is tall．He is a farmer．Where is my grandmother? She is in the kitchen．Look，that is my little brother．This is my big family．