A:Fe:1s22s22p63s23p63d54s3
B:F ˉ:1s22s22p6
C:K:1s22s22p63s23p64s1
D:Kr:1s22s22p63s23p63d104s24p6
①以点O为圆心,任意长为半径作弧,交OB于点D,交OA于点E;
②分别以点D,E为圆心,以大于 12 DE的长为半径作弧,两弧在∠AOB的内部相交于点C;
③作射线OC.
则射线OC为∠AOB的平分线.
由上述作法可得△OCD≌△OCE的依据是( )
工业革命首先开始的国家与部门是( )