15. With the development of West China, many technicians are _____ needed there in recent years.
Mr. White _____ at 8:30 for the meeting, but he didn’t show up.
Only ____from university ____how difficult it was to make a good career.
This is the house _______ I once lived
______ is the richest man in our city?
Xi’an was the last city ______ he visited in China.