1972年，美国总统尼克松访问中国，中美在上海发表《中美联合公报》。该公报的内容不包括（  ）

小萍想利用录音盒、一支滴管、清水及普通放大镜来制作一个显微镜，她组成了如图所示装置，请回答下列问题：

（1）对凸透镜有何要求？

（2）观察时要注意什么？

Tom is from London. He's now in Beijing with his parents. His father and mother teach in a school. He studies in a middle school. The school is four miles from his home. He usually walks to school. He says, "It can make me healthy." Sometimes when it rains, he takes a bus. He's never late, and he's always the first one to get to school. He's good at all his subjects, and often helps us with our English. We all love him very much.