The workmen made so much _____ that Mrs. Walker had to spend three days cleaning up afterwards.

Please don’t ask me to solve mathematical problems; they are beyond my ____.

We take this opportunity to express our sincere         of your timely help.

I think our company lays too much ______ on cost and not enough on quality. 

I listened to Dr．Wilson's lecture about the protection of wild animals, but I was unable to grasp its key     .