12. The little pupil took his grandma __________ the arm and walked her across the street.
A
on
B
by
C
in
D
at
take by拉着，扶着。故选项B符合答案。
根据句意“这个小学生拉着他奶奶的手臂走过了马路。 ”
对介词的含义模糊。