1821年，德国物理学家塞贝克发现了一种怪现象：把两根铜丝和一根铁丝与灵敏电流计串联成闭合电路，然后把铜铁丝的一个联接点放在盛有冰水混合物的容器里保持低温，另一个联接点放在火焰上加热，升到很高的温度时，发现灵敏电流计的指针发生了偏转，表明闭合电路中产生了电流，这就是温差发电现象．问：这一实验是否违反热力学第二定律？简述这一过程中能的转化情况．

在交通事故的分析中，刹车线的长度是很重要的依据。刹车线是汽车刹车后，停止转动的轮胎在地面上滑动时留下的痕迹。在某次交通事故中，汽车的刹车线长度是14m。假设汽车轮胎与地面间的动摩擦因数为0.7，g=10m/s²。则汽车开始刹车时的速度为(        )

________that she is interested in children，I am sure teaching is the right job for her.

一个角有____ 个顶点，有____ 条边。

根据短文内容判断下列句子正误。

    Wednesday，Sep，28th Today was a sunny day．In the morning，Mike and I went to Bruce's home．It was his Birthday．I bought some pencils with different animals for him．He liked them very much．Mike bought him a pencil-box．Bruce's parents bought him a big cake．After we played the chess，we ate the birthday cake and lunch together．We had a good time．