The abacus was invented by Chinese people. A. in the sixth Century B. in the si——青夏教育精英家教网—

摘要： The abacus was invented by Chinese people. A. in the sixth Century B. in the sixtieth Century C. in the sixteenth Century D. in the six Century

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--When _____ the abacus _____? -- In the sixth century by the Chinese people.