译述《天演论》并提出“物竟天择,适者生存”进步观点的思想家是( )
A:严复
B:林则徐
C:魏源
D:孙中山
Mr. Green is very happy because he is satisfied with his students' work today.
2014年7月起,乒乓球国际比赛启用一种新型塑料球.生产这种乒乓球的塑料属于( )