I must have been a great _____ to my parents in those hard days, for I never failed to live up to their expectations.

Many firms give away small quantities of their productions as _______ so that people can try them before buying.

It is always true that sometimes even if you have had a big dinner, _________ are that you will still want to reach for food when it gets late． 

The faces of four famous American presidents on Mount Rushmore can be seen from a _________ of 60 miles.

 The big snow caused great _______to the people living in the south of China, ________some of them homeless.