对未来社会的构想，总体有（    ）两种鲜明的观点。         

如图，⊙O是正五边形ABCDE的外接圆，这个正五边形的边长为a，半径为R，边心距为r，则下列关系式错误的是（　　）

根据句意、释义或中文提示,写出句中所缺单词，使句子通顺。
（1）His parents are angry at his school work. They can't see his ____  (进步)after each exam.
（2）I don't know ____  ( if ) I will have time to join in some activities at school.
（3）Sometimes, I want to ____  (say that you will not do something) to do so much homework.
（4）Orange and yellow are warm colours, they can give you a happy and ____ (满意的) feeling.
（5）Peter is doing an ____  in the laboratory now.

19世纪下半期到20世纪初，一大批发明家在前人科学研究成果的基础上，致力于发明创造，带来了生产和生活方式的变化，推动了人类社会的进步。请以下图人物为例写一篇短文，叙述他的贡献。（提示：内容应包括所属国家、时期、成就、影响等）