There are two blackboards the wall and two doors the wall.A. in inB. on onC. in onD. o

问题补充：

There are two blackboards the wall and two doors the wall.

A. in, in

B. on, on

C. in , on

D. on , in

答案：

A. in, in

B. on, on

C. in , on

(答案→)D. on , in

解析：此题重点考查“在墙上”的两种表达方式，in the wall和on the wall。前者表示镶嵌在墙的里面的事物；后者表示张贴或挂在墙上的东西。因blackboard是挂在墙上的故用on the wall，而doors是镶嵌在墙上的故用in the wall，故选D。