问题补充：
There is a post office the street corner .
A. on
B. in
C. behind
D. across
答案：
(答案→)A. on
B. in
C. behind
D. across
解析：此题考查in the corner和on the corner的区别；都是拐角处的意思，但用法却不一样： in the corner:在里面的拐角处：比如说屋里面的拐角处有一张桌子 There is a table in the corner of the house on the corner:在拐角之上。如在桌子角上放着个杯子 There is a cup on the corner of the table
