Questions are based on the following passage.
For reasons that are deeply rooted in culture and tradition, men significantly outnumber women in mathematics-based careers. As students progress through the mathematics courses, girls and boys show little difference in ability, effort, or interest in mathematics until adolescent years when course and career choices begin influencing school effort. Then, as social pressure increases and career goals are formed, girls' decisions to reduce effort in the study of mathematics progressively cut them off from many professional careers in the future.
Many girls drop mathematics in high school or in the transition to college. Others drop out later. Women perform virtually as well as men in college mathematics courses, but beyond the bachelor's degree women drop out of mathematics at twice the rate of men. Women now enter college nearly as well prepared in mathematics as men, and 46 percent of mathematics baccalaureates (学士学位）go to women. Despite this record, only 35 percent of the master's degrees and 17 percent of the Ph. D degrees in the mathematical sciences are earned by women.
Overall, women receive approximately one third of university degrees in science and engineering. The highest percentages of women are found in those sciences with the least mathematical prerequisite: psychology, biology, and sociology. The lowest percentages of women enter fields requiring the most mathematics, namely, physics, engineering, economics, geo-science, and chemistry. Evidence from many sources suggest that it is differences in course patterns rather than lack of ability that matter most in limiting women's access to careers in mathematically
intensive sciences.
Widely reported studies concerning the high percentage of boys among mathematical prodigies ( 天才. —those who at age 12 perform at the level of average college students—often convey the impression that gender differences in mathematics are biologically determined. But evidence from the vast majority of students shows almost no difference in performance among male and female students who have taken equal advantage of similar opportunities to study mathematics. Inferences ( 推论）from very exceptional students—child prodigies—mean little about the performance of the general population.
According to the author, the learning abilities of males and females in mathematics are similar until they____.