题目

阅读短文，回答问题Do you know why the cat is not in the Chinese zodiac（生肖）? There is a famous Chinesefolk (流传民间的）story about this. The Jade Emperor（玉皇大帝）asks all animals to take part in a race（参加比赛）. The first 12 animals to finish the race will be in the zodiac. Atthat time, the cat and the rat（老鼠） are good friends. Whenthey hear about the race, the cat says to the rat, We should get up earlyfor the race, but I usually wake up late. The rat says he will make hisfriend get up early and they can go together. However, on the morning of在下列图形中，只有一条对称轴的轴对称图形是（　　）A．长方形B．三角形C．等腰三角形D．等边三角形