中国位于亚洲分区中的（　　）

则第七个三角形数是（  ）

如果不动显微镜的其他部分，只是转动转换器，将物镜由10×转换成45×，视野中的光线将会____．

    Yesterday I stepped into a restaurant for lunch. As I was waiting my order to come, I noticed the old man in a wheelchair roll himself over to a table. No one and me seemed to notice him. I got up and go over to his table and asked if that I could get him something to drink. He smiled and said," Thank you. You are generously. I'd like any orange juice, please."When I was getting ready to leave, I walked by the old man's table to saying goodbye. He thanked me again and told me I had made his days, coming over and helping him out. I gave him a hug and told him he had made my day, either.