哺乳动物一般都具有____ 和____ 、体表被毛的特征。

人因大量出血而需输血时，应以输入____为原则．

    Xian Xinghai was a very famous musician in China. He wrote one of the greatest pieces of music of the 20^th century. In his short life he wrote 1 300 songs and an opera.

    Xian was born in Panyu, Guangdong, China in 1905. Because his father died before he was born, Xian moved from place to place with 2 mother. He began learning to play 3 violin when he was 20 years old. In the beginning, his violin was 4 cheap and badly made that he5not play it well. His friends laughed at him. Xian did not stop 6 and soon showed his talent. In 1934, he was one of the first Chinese students7studied in a special music school in Paris. Before he 8, Xian became the school's best student 9 won several prizes for his talents.

    In 1935, he returned to China and helped fight against the Japanese army. Later, he came to Yan'an 10 music at a college. 11 there were no pianos in Yan'an at that time Xian still wrote 12 of his most important music there, including The Yellow River, his most famous work.

    In May 1940, Xian 13 to the Soviet Union by the Chinese Communist Party to write music for movies. In the Soviet Union, life was very 14. Xian got sick and later died of a lung illness 15 October 30, 1945, aged only 40. Xian's music, however, lives on in the people's hearts.

下列关于性状和基因的关系，描述正确的一项是（ ）