abacus
柯林斯詞典
1. N-COUNT An abacus is a frame used for counting. It has rods with sliding beads on them. 算磐
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abacus /??b?k?s/ (abacuses)
劍橋詞典
abacus noun [C] (COUNTING TOOL)
a square or rectangular frame holding an arrangement of small balls on metal rods or wires , used for counting or for doing calculations
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