Teenage is an especially important stage for us, ______we are supposed to go all out to improve ourselves because anything can happen.
Nobody could believe what Chloe says because she is ______ changing her mind.
Don't ______.You will ______ new customs and different ways of thinking.
It______ a calm head to find the best solution to such a difficult problem within a short time.
By the end of 2007,about half a million people had flooded into the city,______ up around 10 percent of its total population.
Jumping out of ______ airplane at ten thousand feet is quite ______ exciting experience.