Questions 14 to 17 are based on the
following passage. At the end of the passage, you will be given 20 seconds to
answer the questions. Now, listen to the
passage.
Which of the following statements is CORRECT
A．Neither the Greek soldiers nor their enemy could understand the messages. B．African soldiers shouted from tower to tower to pass messages. C．Using flags to send messages was found by a French engineer. D．Only by using telephone could people send speech sounds quickly.