A:knew
B:had know
C:have know
D:have been knowr
如图,将长方形纸片ABCD的角C沿着GF折叠(点F在BC上,不与B,C重合),使点C落在长方形内部点E处,若FH平分∠BFE,则∠GFH的度数是____ .
用化学符号填空: