When it comes to “empty-nest syndrome(综合症)”, parents are advised to _______regular contact with children through phone calls, emails, texts or video chats. 

A government spokesman represents the local government’s attitude so he has to ____ his words before responding to reporters. 

---Are you coming to Betty’s wedding? ---I’m not sure. I ______ go to Beijing on business that day.

Judging by her ____, Mrs Smith must be a southerner.    

There are ten ________ teachers and two hundred ________ students in the school.