That may be a hint that yawn evolved as a social cue—"time for us all to go to bed".
也许这是打哈欠进化为社交线索的一种暗示——“到我们大家睡觉的时间了”。
2
It required military discipline to get us out of bed in a chamber warmed only by the stovepipe, to draw on icy socks and frosty boots and go to milking cows.
把我们从只有烟囱才暖和的房间里的床上叫起来，穿上冰冷的袜子和结了霜的靴子，去挤牛奶，这是有军纪的。
3
It's good for us to go to bed early and get up early.