y____-y____

    I like school days. I can learn many things from school. We have four classes in the morning and two in the afternoon. I like weekends, too. We don't go to school on Saturdays and Sundays. I often play ping-pong and play basketball on Saturday morning. I often play the violin (小提琴) on Saturday afternoon. I often do homework and play football on Sunday morning. I often go to the park on Sunday afternoon.

原始大气中没有（    ）

声音与我们的生活有着非常密切的关系，它给我们传来很多____，帮助我们认识周围____。