A、They generally hold bad feelings towards their birth parents. B、They do not want to hurt the feelings of their adoptive parent

When couples get married, they usually plan to have children. Sometimes, however, a couple can not have a child of their own. In this case, they may decide to adopt a child. In fact, adoption is very common today. There are about 60.000 adoptions each year in the United Stales alone. Some people prefer to adopt infants, others adopt older children, some couples adopt children from their own countries, others adopt children from foreign countries.(19)In any case, they all adopt children for the same reason—they care about children and want to give their adopted child a happy life.
    Most adopted children know that they are adopted. Psychologists and child-care experts generally think this is a good idea. However, many adopted children or adoptees have very little information about their biological parents. As a matter of fact,(20)it is often very difficult for adoptees to find out about their birth parents because the birth records of most adoptees are usually sealed. The information is secret so no one can see it. Naturally, adopted children have different feelings about their birth parents. Many adoptees want to search for them, but others do not.(21)The decision to search for birth parents is a difficult one to make. Most adoptees have mixed feelings about finding their biological parents. Even though adoptees do not know about their birth parents, they do know that their adoptive parents want them, love them and will care for them.
Questions 19 to 21 are based on the passage you have just heard.
19. Why do some couples adopt children according to the speaker?
20. Why is it difficult for adoptees to find their birth parents?
21. Why do some adoptees decide not to search for their birth parents?