单项选择题

From the passage, you can tell that people prefer glass fiber cables to copper cables because （）

A．glass fiber is less expensive
B．glass fiber delivers messages directly
C．glass fiber is more up to date
D．glass fiber is easier to make

<上一题目录下一题>

热门试题

单项选择题

According to the passage the new telephone communication system （）

A．has been put into actual use
B．was first put into actual use in 1977
C．had been repeatedly experimented on before 1977
D．was put on experiment in 1977

单项选择题

Before you can hear a message on the telephone using the new system, （）

A．electrical signals must first be changed' into light signals and then into sound
B．the light signals have to be changed directly into sound
C．light must first be changed into electrical signals and then into sound
D．neither the light nor the electrical signals have to be changed in any way