题目

    On a Friday night, a poor young violinist was playing his violin at the entrance(入口)of the subway station. The music was so great that people put some money into his hat.     The next day, the violinist came to the entrance again. He put down his hat as usual. Beside the hat was a piece of paper with some words on it: A George Sang has put an important thing into my hat by mistake. Welcome to claim（认领）it.”After a while a man named George Sang ran here quickly and got back his important thing.     The important thing was a lottery ticket（彩票）.Sang bought 下列实例中不属于生殖隔离的是 [　　] A． 玉米的花粉落在大豆柱头上不能萌发 B． 东北虎和华南虎由于地理原因不能交配 C． 马和驴杂交所生的骡高度不育 D． 不同种类的昆虫雌雄个体之间通常不能交配