阅读理解。 Children become more generous as they get older, learning the principles of equality by the age of eight. That may not be too surprising to anyone who has kids. Humans are born with a sense of fairness that most other animals seem not to share, but it's not been clear exactly when this concept starts to develop. Dr. Alva Zhao and her colleagues conducted a series of tests to measure just how much children care about equality at different ages. In three different versions of a game, children were asked to choose between two ways of sharing a number of sweets with themselves and an unfamiliar partner. They could choose, for example, between one for me and one for you, or just having one for themselves. At the age of three, children were 'almost completely selfish', says Zhao. They refused to give sweets away even if it made no difference to themselves. But by the age of eight, children generally preferred the fair option, sharing a prize equally rather than keeping it all to themselves. Several other factors influenced how fair the children were. The team found that children without brothers or sisters were 28% more likely to share than children with brothers or sisters. On the other hand, the youngest children in a family were 17% less willing to share than children who had only younger brother or sister. In addition, if children knew that their partner was from the same playgroup or school, they were more concerned about being fair. This suggests that being nice to people you know is something that develops a sense of equality. 1. The main idea of the first paragraph is _____. [     ] A. parents know clearly when their kids are more willing to share B. the kids' willingness of sharing is learned from their family C. the older the kids are,the more selfish they will become D. kids become more generous when they reach a certain age 2. The tests conducted by Dr. Alva Zhao and her colleagues were aimed at _____. [     ] A. how kids develop a quality of fairness in games B. children's awareness of equality at different ages C. the reasons why children care about equality D. children's attitudes towards other partners 3. Which of the following is NOT true according to the passage? [     ] A. Children under three know little about being fair. B. Children above eight years old become less selfish. C. Children with brothers or sisters tend to be more generous. D. The youngest child in a family tends to be less generous. 4. We can learn that children care more about equality while with _____. [     ] A. unknown people B. nice people C. familiar people D. fair people