[单选题]In developing a hospital database, it is determined that on the average, each patient will have 6 treatments during a hospital stay.The average length of a stay is three days.The hospital has 1000 beds.There are on the average 800 patients occupying beds each day.The relationship between PATIENT and TREATMENT is 1: M.The relationship between PATIENT and BED is 1:1, conditional.If treatment record occurrences are archived as soon as a patient is discarded from the hospital, how many occurrences of the TREATMENT records will be stored in the TREATMENT database file on the average?

正确答案 ：D

1,600

[单选题]外部设备按数据传输的方式可分为多种类型，通常键盘是哪一种类型的设备？

正确答案 ：B

字符设备

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