PeopleinChinausedtokeeprecordsbyputtinganumberofstonestogether,______

发布时间：2020-08-05 13:49:36

People in China used to keep records by putting a number of stones together, ______?A.usedn’t they toB.did theyC.used to theyD.didn’t they

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D解析反意问句中陈述部分谓语是used to ,是过去式，所以简短问句中要用didn't (they)。
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