21. How did it _____ that humans speak so many different languages?
A. come out B. come off C. come about D. come round
22. You can _____ yourself with a hot bath after a long walk.
A. recover B. reward C. relieve D. refresh
23. The firemen said the fire was under control, but they warned that the changes in the weather might _____ new fires.
A. bring in B. result from C. result in D. break out
