A、Japanese students study much harder than Columbian students. B、Columbian students score higher than Japanese students in maths

The world’s smartest adolescents in mathematics and science are in Singapore, according to a global survey of educational achievement. In the 3rd International Mathematics and Science Study, 13-yearfolds from Singapore achieved the best scores in standardized tests of maths and science that were administered to 287,896 students in 41 countries in 1994 and 1995. The survey suggests that science and maths education is especially strong in the Far East. While well behind those top scores, students from Australia earned higher marks in maths than their counterparts in England, who in turn did better than American students. The study collected information on the students, teachers and homes. Not surprisingly, the highestlscoring students had wellfeducated parents or came from homes containing study aids such as computers, dictionaries or even such elemental facilities as desks. The study shows that boys did generally better than girls in science, but there was little difference between them in maths. Boys scored better than girls in physics and chemistry. There were no sex differences in the life and environmental sciences. In addition to being tested, students in the project were asked how proficient they thought they were in maths and science. Students in some countries, such as Columbia and Kuwait, had an overly optimistic view of their skills. Meanwhile, some of the best students from Japan and Korea for example were need lessly pessimistic even though they did far better in maths than almost all the other students.
Questions 19 to 22 are based on the passage you have just heard.
19. Of the 4 groups of students, who scored the lowest in maths according to the survey?
20. What kind of students are most likely to become top scorers?
21. In what way do Columbian students differ from Japanese students?
22. In which subject did boys score higher than girls?