京剧《澶渊之盟》是一出历史故事剧，其中台词“将舟船暂驻中流，寡人要一观黄河夜景”中的“寡人”指的是历史上的哪位皇帝（    ）

北半球夏季长于冬季是由于（　   ）

甲、乙两名棋手比赛正在进行中，甲必须再胜2盘才最后获胜，乙必须再胜3盘才最后获胜，若甲、乙两人每盘取胜的概率都是$\frac{1}{2}$，则甲最后获胜的概率是（  ）

I will never forget my first English class. It is very interesting. It's the first class in the morning. The teacher goes into the classroom with a smile on his face. At the beginning, he makes a self-introduction(自我介绍). And he tells us that his English name is John. Then he asks all of us to think of English names for ourselves. We are very excited(兴奋的) to find a good name. Then he asks us to write our names down on a piece of paper. I think about my English name for a long time. Then I come up with(想出) a beautiful name ---Shirley. All the students write their names down and give the paper to the teacher. When the teacher calls “Shirley” to answer his question, three girls stand up at the same time.