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问题 单项选择题

对于因( )而发生的债权，债务人未按合同约定履行债务时，债权人有留置权。

A．买卖合同

B．借款合同

C．建设工程合同

D．保管合同

答案

参考答案：D

填空题

票款解行方式：（）。
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单项选择题

Password is a secret series of (73) that enables a user to access a file, computer, or program. On multi-user systems, each user must enter his or her password before the computer will respond to (74) . The password helps ensure that (75) users do not access the computer. In addition, data files and programs may require a password.

A. symbolB. sign C. characters D. characteristic
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