①根据DNA分子的特异性，进行亲子鉴定；

②基于细胞呼吸的原理，采用套种、合理密植、大棚种植等措施增加作物产量；

③在细胞膜的功能研究基础上，开发人工“肾”治疗尿毒症；

④根据染色体变异原理，培育出三倍体无子西瓜．

    It's sunny today. The sun is shining(照耀)in the sky and it's very hot. Nancy goes to the train station(车站)to meet her mother at noon. She walks in the street. There are no trees and she's fat. So she feels very hot. But she doesn't find (发现)a boy walking behind her. And she meets a friend and says "Hello" to him. "Who's the boy behind you?" asks(问) the man. Now she sees the boy. She is angry and asks, "Why(为什么) do you walk behind me, boy?" there's no shade(阴凉处) in the street, you know" answers the boy. "It's cool behind you, I think(想)."