图中4条曲线分别示意北半球中纬度某湖泊的浮游植物生物量与光照、营养物质含量、气温的年变化。若营养物质供应充足,则该湖泊浮游植物大量繁殖大约会持续( )
A:1个月
B:3个月
C:6个月
D:12个月
角形在方格纸中的位置如图所示,则tanα的值是( )
He's never rude. I think he's one of the most _______ boys in his class.