A．How primitive people used flags.B．What the ancient means of communication was.C．Why
A. How primitive people used flags.
B. What the ancient means of communication was.
C. Why the torch towers were built.
D. How the Great Wall came into being.
A．4 hours.B．6 hours.C．12 hours.D．18 hours.
A. 4 hours.
B. 6 hours.
C. 12 hours.
D. 18 hours.
【S6】
A. within
B. by
C. at
D. to
【S16】
A. noises
B. sounds
C. voices
D. rhythms
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