Question

— Did you hear the sound from the traffic light? I wonder________.

— It tells the blind when to cross the street.

A.what it is used for B.when it can stop C.who invented it

Answer

A

【解析】

句意：——你听到红绿灯的声音了吗？我想知道它的用途是什么。——它告诉盲人什么时候过马路。

考查宾语从句。what it is used for它的用途是什么；when it can stop它何时能停；who invited it谁发明了它。根据答语“It tells the blind when to cross the street.”可知它告诉盲人什么时候过马路。所以是回答询问红绿灯声音的用途。故选A。