27.考虑: think about (it)

26.想起　 think of…

25.的标志(象征) the symbol of…

24.以 而闻名: be famous for…

23.最著名的科学家: the best-known scientist

22.生长得更好：grow better

21.制定计划: make a plan

20.越来越少的土地居住　 less and less land to live on

19.有足够住的地方:enough places to live in

18.照顾:　　　　 look after　 (them, her…)