单项选择题
A．when and how the umbrella was invented B．why the umbrella was so popular in Europe C．the development of the umbrella D．the history and use of the umbrella
A．travelling B．holidays C．reading or writing D．thinking during the vacation
A．all nature has come back to life and becomes active B．it is followed by summer C．all kinds of flowers are in full bloom D．it is warm and pleasant