如图甲是探究“物体动能的大小与哪些因素有关”的实验装置，实验中让同一钢球从斜面上不同的高度由静止滑下，撞到同一木块上；图乙是探究“牛顿第一定律”的实验装置实验中让同一小车从斜面上相同的高度由静止滑下，在粗糙程度不同的水平面上运动，请回答下列问题：

关于热现象，下列说法正确的是（　　）

如图是“染色体、DNA分子和基因三者之间关系”的示意图，请据图回答

                                                                              A Trip to the Forest
   One day Bob took two of his friends into the mountains. They put up their tents and then rode off to a forest to see how the trees were growing.
   In the afternoon when they were about ten kilometres from their camp（营地）, it started to snow. More and more snow fell. Soon Bob could hardly see his hands before his face. He could not find the road. Bob knew there were two roads. One road went to the camp, and the other went to his house. But all was white snow. Everything was the same. How could he take his friends back to the camp?
   Bob had an idea. The horses! Let the horses take them back! But what would happen if the horses took the road to his house? That would be a trip of thirty-five kilometres in such cold weather!
   It was getting late. They rode on and on. At last the horses stopped. Where were they? None of them could tell. John looked around. What was that under the tree? It was one of their tents!