当血液通过肺泡周围毛细血管时，氧含量发生变化，下列正确的表示该变化的曲线是（　　）

图为人体某处的血管结构和血流方向示意图．下列有关叙述正确的是（    ）

    Do you kow that animals have love for each other and their children just like us humans? Let me tell you some moving stories of great animal parents.
    Several years ago a heavy rain hit a town and made the river go up. When the rain stopped, people found that a dog swam to an island in the river twice a day for two weeks. Why did she do so? Her four children were there. The mother swam there every day to feed her babies. This true story moved many people.
    Another story is about chimpanzees(猩猩). A scientist named Jane Goodall spent 4 years living with chimpanzees in Africa. She found that chimpanzees also cared for those that were hurt or got lost. “It is not only humans who have duties, animals also do,” she said.
    Two birds in Chengdu also showed their parental(父母的) love. Their baby was hurt and fell on the street in the center of the city. Cars were driving past but the brave parents rushed down to the road and took the little bird away with their claws(爪子).