That may be a hint that the action evolved as a social cue - "time for us all to go to bed" - although as usual when evolution and human behaviour meet, the tie is speculative at best.

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”——不过，像往常一样，当进化和人类行为相遇时，推测充其量只是纽带。

youdao

Then, you've got to stay steady on the shot - don't take a flyer at it because your cue action will just go to pieces.

接下来，在击球动作期间你要保持身体稳定，如果身体不够稳定，那么你的出杆可能就被毁了。

youdao

She gave him tips about wrist action, momentum, angles of incidence, about which part of the cue ball to hit when, and about the need to care just enough that you noticed you cared, but no more than that.

NEWYORKER: Ziggurat