[译] 墙上有个洞。
[误] There is a hole on the wall.

[正] There is a hole in the wall.
[注] on the wall (在墙上)表示在墙的表面;in the wall (在墙里)表示在墙内。而洞只可能在墙内,不可能仅在墙的表面上,所以误句中的on the wall应该为in the wall。如:There are some ink marks on the wall. 墙上有几处墨水迹。