在撞击过程中, 动量的变化是突然的,但非瞬时的.In a crash, momentum changes abruptly but not instantaneously.有时,在局部速度中可能出现瞬时脉动.Sometimes temporal fluctuation may take place inthe local velocity.它表示寻常光波前和非常光波前的瞬时轨迹.It represents the instantaneo...
The prospect of waiting around just twiddling his thumbs was appalling.想到将要无所事事,他就非常害怕。I'm just going to be hanging around twiddling my thumbs.我只会闲呆着,什么事也不做。She had sat there twiddling nervously with the clasp of he...