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问题 多项选择题

ELISA中，若临界质控物检测为阴性，应该核查的问题有（）

A.试剂

B.仪器设备

C.加样操作

D.质控品是否失效

E.病人标本采集、保存是否正确

答案

参考答案：A, B, C, D

单项选择题

Hardin argued that grazing land held in common (that is, open to any user) would always be used less carefully than private grazing land. Each rancher would be tempted to overuse common land because the benefits would accrue to the individual, while the costs of reduced land quality that results from overuse would be spread among all users. But a study comparing 217 million acres of common grazing land with 433 million acres of private grazing land showed that the common land was in better condition.
The answer to which of the following questions would be most useful in evaluating the significance, in relation to Hardin’s claim, of the study described above

A．Did any of the ranchers whose land was studied use both common and private land

B．Did the ranchers whose land was studied tend to prefer using common land over using private land for grazing

C．Was the private land that was studied of comparable quality to the common land before either was used for grazing

D．Were the users of the common land that was studied at least as prosperous as the users of the private land

E．(E) Were there any owners of herds who used only common land, and no private land, for grazing
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单项选择题 A1/A2型题

当无牙颌牙槽嵴吸收严重时，排后牙应将咀嚼中心（即承受牙合力最大的位置）设置于（）。

A.牙槽嵴最高处

B.牙槽嵴最低处

C.牙槽嵴最宽处

D.牙槽嵴最窄处

E.牙槽嵴最平处
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