听下面5段对话或独白。每段对话或独白后有几个小题，从题中所给的[A]、[B]、 [C]三个选项中选出最佳选项，并标在试卷的相应位置。听每段对话或独白前，你将有5秒钟的时间阅读各个小题；听完后，各小题将给出5秒钟的作答时间。每段对话或独白读两遍。
At what time of the year does this conversation take place

A．all tracking stations arc inside Perth, Australia
B．Friendship 7 stopped in the United States
C．radio equipment is important in space flights
D．John Glenn worked alone in the tracking station

A． In a classroom.
B． in an office.
C． At home.