面角不变定律

[机] law of constaney of interfacial angle

miàn jiǎo bù biàn dìng lǜ ㄇㄧㄢˋ ㄐㄧㄠˇ ㄅㄨˋ ㄅㄧㄢˋ ㄉㄧㄥˋ lv4