完形填空

     There is a saying, “No sports, no life.” Sports are very important to us. Sports help us to stay  1  and get good grades. Everyone in our class   2  sports. Our favourite  3  is PE. We only have PE lessons  4  a week, but we play sports every day. The most popular sport in our class is basketball. The boys enjoy  5  it, and many of the  6  like it, too. Another popular sport is football and there   7  a lot of football fans (球迷) in ourclass. When the weather is 8 , we often play ping-pong outside.We hardly ever (几乎不) play volleyball. We think it's  9. We have a basketball team. Our team often has friendship (友谊) matches (比赛) with teams from other schools. When there is a match, many of us go to  10  it. It's very interesting.

假如物体间的摩擦力突然消失，下列哪些现象是不可能的(    )

搜救犬能根据人体发出的气味发现埋在地震废墟中的幸存者，这能说明(   )