With so many difficult problems the manager felt worried all the time.A. settledB. havin

问题补充：

With so many difficult problems , the manager felt worried all the time.

A. settled

B. having settled

C. settling

D. to settle

答案：

A. settled

B. having settled

C. settling

(答案→)D. to settle

解析：考查with的复合结构，with + 宾语 + to do 表示的将来，句意：有如此多的难题要解决，经理一直感到很担忧。问题还没有解决，所以选D。