the call for help the boys immediately rushed out to see what was going on.A. In order

问题补充：

the call for help, the boys immediately rushed out to see what was going on.

A. In order to hear

B. Hearing

C. Having heard

D. They heard

答案：

A. In order to hear

(答案→)B. Hearing

C. Having heard

D. They heard

解析：可联系答.案.网客服索取。