题目

In many developed countries, people who have high degrees begin to work longer than those who don’t. About 65% of American men aged 62－74 with a professional degree are in the workforce (劳动人口), compared with 32% of men who only finish high school. This gap is part of a deepening divide between the well-educated wealthy and the unskilled poor. Rapid technological advance has raised the incomes of the highly skilled while squeezing those of the unskilled. The consequences, for individuals and society, are profound .The world is facing an astonishing rise in the number of old people, 在北方的冬季，常见的几种物态变化现象中，属于凝华的是（　　）A．室外冻冰的衣服变干B．房间窗户玻璃的内表面出现冰花C．湖面结了厚厚的一层冰D．正在跑步的人，口中呼出“白气”