alternatelyadv.交替地，轮流地，轮番地；隔一个地alternatev.交替；轮流adj.间隔的；轮流的；交替的n.代替者；供替代的选择alternate exercise交替练习alternate grafting交替接枝alternate director替补董事alternate matrices交错矩阵alternate activity交替活跃alternate of heart心脏交替现象alternate governor副总裁alternate function交代函数,交替函数alternate-spiral互旋生alternate position预备阵地

1. Read only the alternate lines.
   每隔一行读一行。