Studies show that people are more ______ to suffer from back problems if they always sit before computer screens for long hours. 

A flag is _____ a piece of cloth. It stands for a nation’s people, their land and their history. 　 

My most __________ moment was trying to introduce a woman whose name I couldn’t remember.

The hall was full of people _____ to see the famous actor.

As there is less and less coal and oil, scientists are exploring new ways of making use  of ______________   energy, such as sunlight, wind and water for power and fuel.