单项选择题
A．mothers have the practice to go to work B．working mothers have no time to stay with their children at home C．mother's position in a family has been raised D．young wage-earners are economically independent
A．Why the umbrella was so popular in Europe B．When and how the umbrella was invented C．the history and use of umbrella D．the development of the umbrella
A．The umbrella was first invented to be used as protection against the sun. B．The umbrella changed much in style in the eighteenth century. C．No one exactly knows who was the inventor of the umbrella. D．In Europe, the Greeks were the first to use the umbrell