The difference between the control group and the experimental group was（）

单项选择题The best conclusion we can draw from the passage is that（）

A．parents should be trained to read to their children
B．the more children read, the more intelligent they will become
C．children's language skills increase when they are required to respond actively
D．children who read actively seem six months older

单项选择题In comparison with the adult American population today, tile Americans of the 1910s（）

A．ate more food and had more physical activities
B．ate less food but had more activities
C．ate less food and had less physical exercise
D．had more weight problems