Ⅰ.完形填空
[2015·南京盐城质检二]Why do young adult children become independent so much later than they did in 1970,when the average age of independent living was 21? Why have reduced class sizes and increased perpupil expenditures (花销) not __1__ higher academic achievement levels? Why is the mental health of today's kids so poor when __2__ with that of children in the 1960s and before? Why do today's __3__ become defensive when told by teachers that their children have misbehaved in school?
