(年北京市西城区高三5月二模试题)31. A person who has never tasted bitter won’t know ______ sweet is.
—It is reported that there is big breakthrough in the cancer treatment. —If only his son could be brought back to life!
—I really don’t know when we can get over all the troubles. — ______! Our troubles will soon be over.
Our parents and teachers often ________ the importance of study hard _______ us.
Mr. Smith was the only one of those who ________ to the dinner.
I want to catch _____ early train, but couldn’t get _____ ride to the station.