单项选择题

The passage mainly tells us ________.

A．how to send messages
B．what the Morse code is and how it is widely used
C．the Morse code is used telegraphic code
D．how Morse invented the telegraphic code

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单项选择题

Which of the following is not true according to the passage.

A．SamuelF.
B．Morse invented not only the electric telegraph but also telegraph code.B. The Morse code can be used for communication by telegraph cable or radio.
C．The Morse code is the only telegraphic code in world.
D．When the ships are on the sea, radio operators often use the Morse code.

单项选择题

At sea, ships within sight of each other but out of earshot The underlined word means______.

A．the ear was shot
B．a man' s
C．can't hear
D．hearing distance