Questions 38 - 40
One of the problems of owning a cell phone is that it must be charged from time to time.
But this could soon be a thing of the past. A scientist in South Korea, Dr. Sang-Woo Kim, has found
a way to charge a cell phone using the human voice. Soon you might be able to recharge your phone
just by talking into it. When people talk, their voices produce energy in the form of sound waves.
Dr. Kim has invented a machine, small enough to fit inside a cell phone, which changes those
sound waves into energy. Dr. Kim is hoping to see his new idea used in future phones. In the
near future, charging your phone and talking with a friend could be one and the same.
【題組】39. Which of the followings is the closest in meaning to the underlined phrase “from time to time”?
(A) regularly (B) many times (C) all the time (D) once in a while