A.彈力纖維 B.疏松的膠原纖維 C.堅(jiān)實(shí)的膠原纖維 D.柱狀上皮細(xì)胞
A.會(huì)聚光束 B.發(fā)散光束 C.平行光束 D.像散光束
A.鎳和鈷 B.鎘 C.銅和硒 D.錳