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问题 单项选择题

关于质粒的叙述，错误的是（）

A.质粒是细菌核质外的遗传物质

B.质粒能在胞浆中自行复制

C.质粒可以丢失

D.质粒是细菌生命活动所必需的结构

E.某些细菌的耐药性与质粒有关

答案

参考答案：D

解析：质粒并非细菌生命活动所必需的，只能控制细菌的某些性状，可以丢失。

单项选择题

脑内出血最常见原因为（）

A.高血压病

B.血液病

C.血管瘤破裂

D.颅脑损伤

E.动静脉畸形
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单项选择题

TCP/IP （） layer protocols provide services to the application （） running on a computer. The application layer does not define the application itself, but rather it defines （） that applications need—like the ability to transfer a file in the case of HTTP. In short, the application layer provides an （） between software running on a computer and the network itself. The TCP/IP application layer includes a relatively large number of protocols, with HTTP being only one of those. The TCP/IP （） layer consists of two main protocol options—the Transmission Control Protocol (TCP) and the User Datagram Protocol (UDP).

but rather it defines （） that applications need—like the ability to transfer a file in the case of HTTP.

A.services

B.processes

C.applications

D.address
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