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【单选题】
Bluetooth When you use computers, entertainment systems or telephones, the various pieces and parts of the systems make up a community of electronic devices. These devices communicate with each other using a variety of wires, cables, radio signals and infrared light(红外线) beams, and an even greater variety of connectors and plugs. The art of connecting things is becoming more and more complex every day. And Bluetooth has now become a new popular method of connecting devices that can streamline the process. A Bluetooth connection is wireless and automatic, and it takes small-area networking to the next level by removing the need for user intervention and keeping transmission power extremely low to save battery power. Bluetooth Operation Bluetooth networking transmits data via 10w-power radio waves. It communicates on a frequency of 2.45 gigahertz(千兆赫)(actually between 2.402 GHz and 2.480 GHz, to be exact). This frequency band has been set aside by international agreement for the use of industrial, scientific and medical devices(ISM). A number of devices that you may already use fake advantage of this same radio-frequency band. Baby monitors(微型监视器), garage-door openers and the newest generation of cordless phones all make use of frequencies in the ISM band. One of the ways Bluetooth devices avoid interfering with other systems is by sending out very weak signals of about 1 milliwatt. By comparison, the most powerful cell phones can transmit a signal of 3 watts. The low power limits the range of a Bluetooth device to about 10 meters(32 feet), cutting the chances of interference between your computer system and your portable telephone or television. Even with the low power, Bluetooth doesn't require line of sight between communicating devices. The Walls in your house won't stop a Bluetooth signal, making the standard useful for controlling several devices in different rooms. Bluetooth can connect up to eight devices simultaneously. With all of those devices in the same 10-meter(32-foot) radius you might think they'd interfere with one another, but it's unlikely. Bluetooth uses a technique called spread-spectrum.(扩展频谱) frequency that makes it rare for more than one device to be transmitting on the same frequency at the same time. In this technique, a device will use. 79 individual, randomly chosen frequencies within a designated range, changing from one-to another on a regular basis. In the case of Bluetooth. the transmitters change frequencies 1,600 times every second, meaning that more devices can make full use of a limited slice of the radio spectrum. Since every Bluetooth transmitter uses spread-spectrum transmitting automatically, it's unlikely that two transmitters will be on the same frequency at the same time. This same technique minimizes the risk that portable phones or baby monitors will disrupt Bluetooth devices, since any interference on a particular frequency will last only a tiny fraction of a second. Piconets(个人域网络) Let's say you have a typical modern living room with the typical modern Stuff inside. There's an entertainment system with a stereo, a DVD player, a satellite TV receiver and a television there's also a cordless telephone and a-personal computer. Each of these systems uses Bluetooth, and each forms its own piconet to talk between the main unit and peripheral(外围设备). The cordless telephone has one Bluetooth transmitter in the base and another in the handset. The manufacturer has programmed each unit with an address that falls into a range of addresses it has established for a particular type of device. When the base is first turned on, it sends radio signals asking for a response from any units with an address in a particular range. Since the handset has an address in the range, it responds, and a tiny network is formed. Now, even if one of these device
A.
Y
B.
N
C.
NG
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【单选题】我国的科举考试制度萌芽于( )
A.
隋朝
B.
唐朝
C.
魏晋南北朝
D.
以上都不是
【单选题】某孕妇,妊娠25周。骨盆测量显示中骨盆、出口平面狭窄,属于
A.
均小骨盆
B.
畸形骨盆
C.
漏斗骨盆
D.
正常骨盆
E.
扁平骨盆
【多选题】收益资本化规律有着广泛的运用,以下关于土地价格的说法正确的是( )
A.
当利率不变时,土地预期收益越低,土地价格越低
B.
当预期收益不变时,市场利率越低,土地价格越高
C.
当预期收益不变时,市场利率越高,土地价格越低
D.
当利率不变时,土地预期收益越低,其价格越高
【多选题】收益资本化规律有着广泛的运用,以下关于土地价格的说法正确的是( )
A.
当预期收益不变时,市场利率越高,土地价格越低
B.
当预期收益不变时,市场利率越低,土地价格越高
C.
当利率不变时,土地预期收益越低,其价格越高
D.
当利率不变时,土地预期收益越高,其价格越低
E.
当预期收益不变时,市场利率越低,土地价格越低
F.
当利率不变时,土地预期收益越低,土地价格越低
【单选题】下列关于船舶沿岸雾航的说法中,何者正确 。
A.
应尽可能使航线与岸线总趋势平行
B.
主要使用雷达瞭望,目视瞭望是次要的
C.
采用逐点航法能确保船舶航线安全
D.
雾中航行,能否听到他船雾号,是判断是否存在航行危险的关键
【单选题】某孕妇,妊娠 25 周。骨盆测量显示中骨盆、出口平面狭窄,属于
A.
扁平骨盆
B.
漏斗骨盆
C.
均小骨盆
D.
畸形骨盆
E.
横径狭小骨盆
【单选题】某孕妇,妊娠 25 周,骨盆测量显示中中骨盆,出口平面狭窄,属于( )
A.
扁平骨盆
B.
漏斗骨盆
C.
均小骨盆
D.
畸形骨盆
E.
横径狭小骨盆
【单选题】少尿是指一昼夜尿量少于
A.
50ml
B.
lOOml
C.
300ml
D.
400ml
E.
500ml
【多选题】收益资本化规律有着广泛的运用,以下关于土地价格的说法正确的是( )
A.
当预期收益不变时,市场利率越高,土地价格越低
B.
当预期收益不变时,市场利率越低,土地价格越高
C.
当利率不变时,土地预期收益越低,其价格越高
D.
当利率不变时,土地预期收益越高,其价格越低
E.
当预期收益不变时,市场利率越低,土地价格越低
【简答题】Passage One “Humans should not try to avoid stress any more than they would shun food, love or exercise.” said Dr. Hans Selye, the first physician to document the effects of stress on the body. While ...
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