---There is a book on the ground.---Let’s and ask who lost it.A. lies pick it ourB. lyi

问题补充：

---There is a book on the ground.

---Let’s and ask who lost it.

A. lies, pick it our

B. lying, pick it up

C. to lie, pick up

D. lying,pick out it

答案：

A. lies, pick it our

(答案→)B. lying, pick it up

C. to lie, pick up

D. lying,pick out it

解析：句意：---在地上有一本书，---让我们把它捡起来问问是谁丢的。There be +主语+doing+介词短语，表示某处有某物正做某事，lie的分词是把ie变y+ing, pick up捡起，拾起，如果是代词放在中间，结合语境可知选B。