头部下垂：指头部向下倾斜或下垂的姿势或动作。
落差
... head carry (救生)托头拖带法 head drop 低头 header 头往下入水 ...
... head水头 head drop落差 head loss水头损失 ...
... 把头 gang master; labor contractor / gangmaster; labour contractor 头垂病 head drop; nose drops 垂下的 lop; suspended ...
（水等的）落差；低头
She let her head drop.
她把头垂了下来。
Already out there, that the rain hat because her head drop off the snow.
说是早已等在那里，是因为她头上的斗笠落了雪。
Try to toss the ball into the same spot every time? Let your racket head drop behind you and then hit the ball suddenly.
尽量在发球时每次都把球抛到相同的位置，然后将球拍举到头后方，瞬间击球。
The Head of the Russian Parliament's Foreign Affairs Committee, Konstantin Kosachev, has welcomed Washington's decision to drop plans for the missile defense system.
VOA : standard.2009.09.17
If we let our head drop, our heart drops with it.
Drop my head a little bit, do the eyebrows.
"For him to go off nice and relaxed in 24 and change and come home on his own the way he did, and gallop out the way he did, and drop his head and walk home, it sent cold chills up my back, " the Hall of Fame trainer said.