Paul: Hey, Jenny, the subject for my school project is "Small invention that changed the world". Can you help me think of an invention?

Jenny: With ____! Let me think ... hmm ... I know! The zipper!

Paul: The zipper? Is it ____ such a great invention?

Jenny: Think about how often it's used in our ____ lives. You can see zippers on dresses, trousers, shoes, bags ... almost everywhere! I saw a website last week. The ____ of different inventions were listed there. For example, it mentioned that the zipper was ____ by Whitcomb Judson in 1893. But at that time, it wasn't used widely.

Paul: So when did it become popular?

Jenny: Around 1917.

假定一个草原是由鹿和狼组成的相对封闭的生态系统，若把狼杀绝，鹿群的数量将会（  ）

法国史学家米西勒认为，14到16世纪的欧洲封建社会末期是“人”和“世界”被发现的时代。这两个“发现”对世界历史产生的共同影响是（    ）

球O的球面上有四点S，A，B，C，其中O，A，B，C四点共面，△ABC是边长为2的正三角形，平面SAB⊥平面ABC，则棱锥S﹣ABC的体积的最大值为____