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

Managers in excellent companies have a strong _____ for doing things rather than talking about situations.

Children need friends ______ their own age to play with. 

A sense of __________ is the basic requirement for people working in the service industry, such as education and health care.

This house will probably come on the ______ next month.