题目

The Beatles, ______ many of you are old enough to remember, came from Liverpool.       A．what                     B．that                     C．how                    D．as   答案：D．解析：本题考查在实际语境中对于非限制性定语从句的应用能力。声音是由物体________产生的；声音在15℃的空气中传播速度是________m/s．