A. year mod 4=0 B. year mod 400=0 C.(year mod 400=0)or(year mod 4=0)and(year mod 100<>0) D.(year mod 400=0)and(year mod 4=0)or(year mod 100<>0)
A.4*D B.A_B C.4ABC D.A+B
A.(x<=4)and(x>=6) B.(x>4)Or(x>6) C.(x>=4)Xor(x>=6) D.not(x<>4)