问题

The employees were asked to concentrate their attention________improving the quality of the products.[ ]

A: in
B: to
C: with
D: on

正确答案是：

同类题型

下列各句，没有语病的一项是（）

He lost both of his parents in the big earthquake,but ________ for him,a kind couple adopted him and took good care of him [ ]

__________ Jane is only five years old, she can play the piano well.

When you retell stories, you can ____ the unimportant details.[ ]

He was about to jump into the river ________ his mother stopped him[ ]