电脑硬盘的盘片表面涂覆有一层y—Fe2O3磁粉。y—Fe2O3中铁元素的化合价为 请选择DCBA:u1{5J8t5@0B4W*{:I9P
A．04W*{:I9P
B．+14W*{:I9P
C．+24W*{:I9P
D．+34W*{:I9P