By now, when one makes a large purchase, he should have ___ opportunity to change his mind.

Some students, hoping to get a high score, are _______ about the results of coming exam.

— You looked so ______, what’s the matter?— I’ve had a very trying time this afternoon. I had to spend the whole listening to the _____ lecture by Mr. Smith.

----“This book is ______ more useful for us students.”----“Yes, but it is _______ too difficult.”

—What do you think of this matter?  —This is a matter of __________ importance. I think.