题目

The outstanding biography — from the same author who brought us Steve Jobs and Einstein —portrays the life of the complicated Renaissance (文艺复兴时期的) artist with details. We come to see da Vinci as not only an inventor of musical instruments and early flying machines, but also a notebook keeper and vegetarian (素食者), who had trouble finishing many of the projects and paintings he started.Yet what is most thrilling is getting to know da Vinci the scientist. Isaacson explains how loving science and applying the scientific method to observing the world was really what made da如图，请写出一个能说明CE∥AB的一个条件________；