There is a ball（ ）the chair.填介词.填on是错的.My father 【 】（finish ）his work in an hour.我原本填的也是has finished 可是老师批的是错的 We 【 】（hold）the 2010 EXPO in shanghai。

There is a ball（ ）the chair.填介词.填on是错的.My father 【 】（finish ）his work in an hour.我原本填的也是has finished 可是老师批的是错的 We 【 】（hold）the 2010 EXPO in shanghai。
There is a ball（ ）the chair.填介词.填on是错的.My father 【 】（finish ）his work in an hour.
我原本填的也是has finished 可是老师批的是错的
We 【 】（hold）the 2010 EXPO in shanghai。

There is a ball（ ）the chair.填介词.填on是错的.My father 【 】（finish ）his work in an hour.我原本填的也是has finished 可是老师批的是错的 We 【 】（hold）the 2010 EXPO in shanghai。
in; under
will finish 严格地说不能填finished..555
We (are holding) the 2010 EXPO in Shanghai.

under, will finish, are holding 我的没有错，呵呵。相信我。(⊙o⊙)
祝您学习进步，更上一层楼！如果答案您满意，请记得采纳，谢谢！O(∩_∩)O

under
has finished