问题补充：
--Where is the post office?
--Just go straight and turn. It is .
A. left; to the left
B. left; on the left
C. on the left; left
D. left; left
答案：
A. left; to the left
(答案→)B. left; on the left
C. on the left; left
D. left; left
解析：固定词组搭配，turn left /right ，on the left /right，故选答案为B
