亚洲色精品Aⅴ一区区三区_国产丝袜一区二区在线播放91_亚洲av电影在线观看_欧美精品AⅤ在线视频:

intro:
Color: Silver white;
Density: 2.99, m.p.: 1541; B.P.: 2830.
It is mainly used in the manufacture of semiconductor transistor etc.