by hand为什么不说by hands

by hand为什么不说by hands 为什么是 by hand 不是 by hands hand by hand be picked by hand 被用手采摘 为什么是hand不是hands? 为什么只能用by the hand 不能用by the hand?by her hand 打错了 The cake is so big.How did your mother make it?She made it[【】A.with hand B.in hand C.by hands D.by hand almost all the work in the factory is no longer done----A by hand B with hands C in hand Father By The Hand “at hand,in hand,on hand,by hand”分别是什么意思? 请问下hand by hand的意思 是with hand 还是by hand? hand by hand,never get lost! by hand 与 by the hand的区别 by hand 与 by the hand的区别 ●hand by hand 手拉手,heart by heart she held me (by)the hand and said ,''you are a good boy.''为什么用by take sb by the hand Father By Thy Hand 歌词