市场有效细分的条件是()。
A. 差异性
B. 可进入性
C. 灵活性
D. 可衡量性
E. 可盈利性
He sat silent in the corner. He was reading his favorite novel.
When she saw the traffic light turn green, she quickly crossed the road.
As he has engaged in the research for many years, he is quite familiar with the topic.