题目

有“绿色水库”之称的生态系统是                                    （     ） A．草原生态系统                                   B．森林生态系统        C．农田生态系统                                  D．城市生态系统 答案：BTelevision has many advantages. It keeps us      about the        news and also provides entertainment.          A．informed; lasted        B．to know; later    C．learning; latter  D．to think; latest