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duoduolingyu:發(fā)光方向可以選擇垂直于該表面 (2017-11-07 18:46) &<+ A((/i
thorn12345:你說(shuō)的那個(gè)是發(fā)散角的問(wèn)題,不是方向問(wèn)題,垂直于該表面、但是方向朝哪? (2017-11-08 08:18) F3oQ^;xB