When carbon is added to iron in the proper proportions , the result is steel.
D
暂无解析
Communicationisoneofthemostimportantbondsthatholdculturalsystemstogether.
WhileBillieHolidaydidnotinventthemusiccalled"theblues",shemostassuredlyhelpedpopularizeit.
Eyespots,themostrudimentaryeyes,arefoundinprotozoan原生动物flagellates鞭毛虫,flatworms扁形虫,andsegmentedworms片段蠕虫.