单项选择题

The reference word "it" ( Sentence 1 , Para. 3 ) refers to ______.

A．the air
B．the ocean
C．the laser beam
D．the submarine
<上一题 目录 下一题>
热门 试题

单项选择题
Who would be very much interested in the passage
A．Missile builders.
B．Fishermen.
C．Military scientists.
D．Ship builder.
单项选择题
Which of the following is NOT true of a laser system
A．It is able to make its way through water.
B．It is able to communicate with submarines at work.
C．Its beam reaches a submerged submarine with the help of an antenna.
D．It is able to carry more data than low frequency waves.
相关试题