四、長篇閱讀(第 41−50 題)
說明：下列二篇文章共有 10 個問題，閱讀後請依文意與題意選出最恰當的選項，並將代號
標示在答案卡上。
The electricity generated by a power plant and delivered to your home by your local utility is
called alternating current (AC) because it flows alternatively, first in one direction then in the opposite,
completing 60 cycles every second. Batteries produce DC or direct current. From the power plant,
current travels over high-voltage transmission lines to substations, where transformers reduce the
voltage for distribution to local lines. Neighborhood transformers lower voltage to 120 and 240 volts
for home delivery.
Most homes built after World War II have three-wire electrical service, in which a neutral wire
and two 120-volt hot wires provide 100 to 200 or more amps at both 120 and 240 volts. Older homes
may still have two-wire service, in which one neutral and one hot wire deliver 30 to 60 amps at 120
volts only.
Electrical service may be routed to a home through overhead wires running from the nearest
utility pole to the service entrance head located high on one side of the house. Here the utility’s wires
are spliced to the service entrance wires, which are usually encased in metal or plastic tubing, called
conduit, or combined in a service entrance cable. From the service head, the wires pass through a meter,
which records your electricity use, and into the main service panel, where current is split and distributed
through branch circuits throughout the house. Alternatively, electric service may be routed
underground to a home.
【題組】42.aAccording to the passage, which of the following is correct?
(A) Most modern homes use two-wire electrical service.
(B) Three-wire electrical service has one hot wire.
(C) Lowering electric voltage is necessary for electricity use in a house.
(D) Local utility company provides direct current electricity.
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