下图为卫星拍摄的冰山照片。图片中显示R冰山(69°24′S,100°12′E)已经从南极大陆边缘厚冰层中解体出来，它东西最宽处约13千米，南北长约24千米。目前，R冰山正在向该地区的东部海域缓缓移动。据此，监测R冰山移动方向和速度最好采用（    ）。

关于速度和加速度的关系，下列说法中正确的是（   ）

阅读下列短文，从每题所给的四个选项（A、B、C和D）中选出最佳选项。

    Are you sorry for not traveling during the National Day? If you stay at home at that time, I think you are very lucky. Why? Because there are too many people everywhere. In many places of interest in China, it's too crowded to do anything.

    Look at the picture. It was too crowded on the Great Wall on October 1st, 2015. You even couldn't take photos for you or your friends. All what we could see were people. It was reported that there were about twenty people every meter on the Great Wall. My friends told me they could see nothing but many people on the Great Wall. "We couldn't walk if the people in front of us didn't walk," he said. He showed us a photo on the Great Wall. In the photo, we hardly found him out, there were too many people.

    So some people give the advice that we should not have the gold week any more. But other people say no about this advice. What's your idea of it? Are you sorry now for not traveling during the gold week? I love staying at home more than traveling next National Day.