A:such; that
B:so; that
C:too; that
D:too; to
如图,FD⊥AO于D,FE⊥BO于E,下列条件:①OF是∠AOB的平分线;②DF=EF;③DO=EO;④∠OFD=∠OFE.其中能够证明△DOF≌△EOF的条件的个数有( )
如图表示人的个体发育过程.请据图回答:
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