【题目】The little pupil took his grandma the arm and walked her across the street.
A.on
B.by
C.in
D.at

【答案】B
【解析】句意：这个小学生拉住他奶奶的膀子和她一起穿过街道。take sb. by the arm固定短语”拉住某人的膀子“，所以选B。