More bison were killed.The bison population is thought ______ from 60 million to just a few hundred between 1850 and 1910.
It was not until the end of the trip ______ I realized what a good feeling it was to have helped someone in trouble.
As a Chinese saying goes, a mountain ______ be too high or an ocean too deep. Therefore, there is no end to our self-improvement.
Sometimes I act as a listening ear for fellow students ______ what is bothering them.
An increased concentration of carbon dioxide and certain other gases in the Earth’s atmosphere ______ global warming.
New York State has passed a law requiring that all legal contracts _____ in simple, understandable English.