题目内容
改写句子，在空格内填入必要的词：A. People in China used the abacus (算盘) centuries ago.
B. The abacus was ______ in China several hundred years ago.
答案：used
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题目内容
改写句子，在空格内填入必要的词：A. People in China used the abacus (算盘) centuries ago.
B. The abacus was ______ in China several hundred years ago.