A-A+
A．To indicate how climbers communicated.B．To s
问题详情
A．To indicate how climbers communicated.
B．To show that climbers enjoyed many comforts.
C．To show that modern telephones work at high altitudes.
D．To emphasize how small some equipment had become.请帮忙给出正确答案和分析，谢谢！
参考答案
正确答案：D
解析：Why does the speaker mention a hand-held telephone?
推理题。解答此题的关键是通过和过去的落后进行对比(in the past．．．much too heavy．But now．．．have been reduced to．．．)推导出对现在进步的肯定(emphasize how small)。
