Class is over. The students stop and start .
A:writing; to talk
B:to write; talk
C:writing; talk
D:to write; talking
选出有错别字的一项。( )
阅读诗歌,回答问题
次北固山下
王湾
客路青山外,行舟绿水前。
潮平两岸阔,风正一帆悬。
海日生残夜,江春入旧年。
乡书何处达?归雁洛阳边。
地球上最大的生态系统是( )