保安员的职责是指保护国家财产安全

( )又称机械抽样、系统抽样，是将个体按某一特性排队编号后均分为几组，这时每组有K=N/n个个体，然后在第一组内随机抽取第一件样品，以后每隔一定距离 (K号)抽选出其余样品组成样本的方法。

A．简单随机抽样

B．等距抽样

C．多阶段抽样

D．分层抽样

患者，女，60岁。因突然意识不清1小时送急诊，头颅CT显示右侧大脑半球3cm×3cm×6cm高密度影，临床诊断为脑出血。此病人降低颅内压，可选择的药物不包括（）。

A.白蛋白

B.甘露醇

C.甘油果糖

D.硝普钠

E.呋塞米

阅读下面一首词回答问题。

1、词的上片写了哪些夏夜特有的声音？写这些声音有何作用？

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2、词的下片给人们展示了一幅怎样的画面？试用简洁优美的语言进行描绘（100字内）。

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MIDI enables people to use (11) computers and electronic musical instruments. There are actually three components to MIDI, the communications" (12) .", the Hardware Interface and a distribution (13) called "Standard MIDI Files". In the context of the WWW, the most interesting component is the (14) Format. In principle, MIDI files contain sequences of MIDI Protocol messages. However, when MIDI Protocol (15) are stored in MIDI files, the events are also time-stamped for playback in the proper sequence. Music delivered by MIDI files is the most common use of MIDI today.

A．device

B．protocol

C．network

D．controller

热电厂的厂址应占用荒地、次地和低产田，不占或少占( )。

A．良田
B．菜地
C．耕地
D．树林