1. Two bags of flour weigh the same, from the first bag $\frac{1}{3}$ is used, from the second bag $\frac{1}{3}$ kilogram is used, the remaining flour ( ).
(A) the first bag is heavier
(B) the second bag is heavier
(C) both bags weigh the same
(D) it cannot be determined which bag is heavier
D

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