下列国家中不属于东亚的国家是（　　）

下列速度指瞬时速度的是（   ）

①子弹出膛的速度             

②足球被踢出时的速度

③火车通过甲、乙两地间的速度 

④子弹头过某点的速度．

半径相同的两个金属球A、B都带有大小相等的电荷量Q，相隔一定距离，两球之间相互吸引力的大小是F.，今让第三个半径相同的不带电的金属小球先后与A、B两球接触后移开．这时A、B两球之间的相互作用力的大小是   (　　)

阅读短文，根据短文判断正误，用T或F表示。

A

The Marathon

The marathon is the longest race at the Olympics. You have to be a very strong runner to win the marathon.

The marathon is 42.195 km long. Why is it 42.195 km and not 43? The 1908 Olympics was in London. The King of England wanted his children to watch the marathon so the race started at the gate of his palace. From there to the finish line was 42.195 km.

One of the best marathon runners was Abebe Bikila. He was from Ethiopia. He won the gold medal in the marathon at the 1960 Olympics. He ran the whole race without shoes on!