I believe that each of us can c___ to the future of the world.
Circumstances have __________ (联合) to ruin our plans for a holiday.
He is very d__________ because he failed in the examination.
Hearing what he was saying, a question naturally p__________ itself in my mind.
I feel it a great __________ (荣幸) to give a lecture to you.
The c__________ of stamps is housed in a fine building.