New research says that children of older mothers grow up to be happier. It also says these children will have fewer behavioral, social and emotional problems. Researchers from a university in Denmark looked at data from 4,741 mothers with the average age of the mothers when pregnant being 31. Older mothers worry less during pregnancy. They are usually happier and more positive about becoming parents and about children. This may mean they are more caring. Older mothers also have more stable relationships. They have more money, and they have a better education. Researchers also found that children with older mothers have better language skills than those with younger mothers. This may be because older mothers spend more time with their children and talk to them more. 36. What is the main idea of the paragraph? A. Being older mothers is better than becoming young mothers. B. Older mothers don’t care much about having babies. C. Why children of older mothers tend to be better than those having young mothers D. The relationship between mothers and children. 37. By what was the research in the paragraph carried out? A. An educational institution B. Behavioral scientists C. A childcare organization D. Households 38. What is NOT a reason that makes older mothers take better care of their children? A. They have stable relationships. B. They have more kids. C. They are wealthier. D. They are better-educated. 39. According to the paragraph, which of the following statement is correct? A. There are more and more older mothers. B. Children having older mothers tend to behave badly and emotionally. C. Talking more to small children can help them have better language skills. D. Children of older mothers grow up to be happier. 40. What is the meaning of the word “them” in the last sentence? A. older mothers B. younger mothers C. older mothers’ children D. younger mothers’ kids