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问题 单项选择题

牛奶是钙良好的食物来源，每毫升牛奶中含钙量约为（）。

A.180～200mg

B.140～160mg

C.50～70mg

D.100～120mg

E.70～90mg

答案

参考答案：D

单项选择题

In a public-key cryptosystem, (71) encrypted with the public key can only be deciphered with the private key from the same (72) . Conversely, (71) encrypted with the private key can be decrypted only with the public key. Users can make their public keys (73) available or place them at a key distribution center or others to access. However, the private key must be (74) safe. In public-key systems there’s no (75) to find a safe channel for communicating a shared secret key.

A. keepB. keeped C. keeping D. kept
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单项选择题

故意不建立账簿，隐瞒经营收入和营业额；违反财经制度，建立明暗两本账。这些行为属于（）

A.偷税

B.欠税

C.骗税

D.抗税
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