正确答案: ABC

2.23 2.24 2.25

题目：下面属于密封铅酸蓄电池在25℃时的浮充工作电压范围有()V。

解析：ABC

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举一反三的答案和解析：

[多选题]【 The Internet ofthings (IoT) is the inter-networking ofphysical devices，vehicles ，buildings ，and other items embedded with electronics ，software，sensors，actuators，and network connectivity which enable these objects to collect and exchange data. In 2013 the Global Standards Initiative on Internet ofThings (IoT-GSI) defined the 10T as " a global infrastructure for the information society， enabling advanced services by interconnecting (physical and virtual) things based on existing and evolving interoperable information and communication technologies" and for these purposes a "thing" is "an object ofthe physical world (physical things) or the information world (virtual things). which is capable ofbeing identified and integrated into communication networks". The 10T allows objects to be sensed or controlled remotely across existing network infrastructure ，creating opportunities for more direct integration of the physical world into computer - based systems，and resulting in improved efficiency. Accuracy and economic benefit in addition to reduced human intervention. When IoT is augmented with sensors and actuators，the technology becomes an instance of the more general class of cyber­ physical systems，which also encompasses technologies such as smart grids，virtual power plants ，smart homes ，intelligent transportation and smart cities. Each thing is uniquely identifiable through its embedded computing system but is able to interoperate within the existing Intemet infrastructure. Experts estimate that the 10T wi l1 consist of about 30 bi l1ion objects by 2020. 】 Based on the paragraph above，we know that the applications ofthe 10T include (98) . RFID technology makes it possible to automatically (99) every object on the Internet ofthings，and is the foundation ofnetworking. From the industry point of view，IoT is mainly involved in industries including (100).

environmental monitoring

all ofthe above

解析：D,A,D

[单选题]运算器包括一定数目的二进制位，该数目称为运算器的字长。以下关于字长的叙述中，不正确的是：（84） 。

字长越长，一般而言运算精度也就越低

[单选题]OFDM将宽带传输转化为很多子载波上的窄带传输，每个子载波上的信道可以看作()信道

平坦衰落

[单选题]密封铅酸蓄电池在环境温度为25度条件下，浮充工作端电压范围()V。

2.23～2.27

[多选题]目前提出的数字通信网的同步方式主要有（）。

主从同步方式

互同步方式

准同步方式

解析：ACD

[单选题]根据移动多媒体广播电视业务发展需要，下列哪项不是移动多媒体广播电视业务平台()

普通业务平台

[单选题]空调器制冷系统的心脏是()，制冷剂的循环流动都靠它实现。

压缩机

[多选题]全国数字同步网监控管理系统的结构可分()。

全国监控管理中心

省级监控管理中心

本地监控管理中心

解析：ABC

[单选题]为提高物理线路的使用率，电信网的传输系统通常都采用多路复用技术，如PSTN网络和GSM网络的局间中继线路传输均采用（）复用技术。

同步时分