sound of footsteps in a deserted valley; rare,unusual guest; unexpected good news
❍ 这一消息真如～，使人欢欣鼓舞。This news was as rare as the sound of footsteps in a deserted valley and it filled the people there with joy.
空谷足音kong gu zu yin
footsteps one hears in a deserted mountain valley—valuable information or opinion that is dificult to come by
空谷足音kōnɡ ɡǔ zú yīn
在空山谷里听到人的脚步声。比喻非常难得的音信或事物。difficult to meet with, unexpected good news; rare, welcome appearance