Everyone has such a busy life that sometimes it becomes tough to _____ with it.
When ______ comes to research into heart disease and its effects on the body, we do not have adequate substitutes for the use of animals.
Environmental experts point out that ______ some serious problems such as global warming, but it also could threaten human life.
—I heard that Mr. Smith has become a triathlete. —Oh, really? He has become ______ he wanted to be.
China Mobile, which has cut its charges in recent years, is desperate to find new income sources ______ its traditional services.
The stars are so hot that they ______ great light and heat — more than the hottest, brightest fire you can imagine.