单项选择题
A.Integer B.Boolean C.Single D.String
A.1-2+3-4+…+(-1)n*(n-1) B.1-2+3-4+…+(-1)n-1*n C.1+2+3+4+...+(n-1)+n D.-1-2-3-4-...-n
A.A=B;B=C;C=A B.C=A;A=B;B=C C.A=B;B=A D.C=A;B=A;B=C