题目内容：
Directions: In this part, you will have 15 minutes to go over the passage quickly and answer the questions on Answer Sheet 1.For questions 1 - 4, mark
Y (for YES) if the statement agrees with the information given in the passage;
N (for NO) if the statement contradicts the information given in the passage;
NG (for NOT GIVEN) if the information is not given in the passage.
For questions 5-10, complete the sentences with the information given in the passage.
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 low-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 take 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 bas
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