A.15B.20C.25D.30
A.隔離物變得暗淡無(wú)光或呈微黃色B.含有錳質(zhì)時(shí)則呈現(xiàn)紫色C.含有鐵質(zhì)時(shí),顏色變?yōu)闇\紅色D.極板顏色變深
A.監(jiān)聽(tīng)B.調(diào)試C.改造D.自環(huán)測(cè)試