The wreckage of something like a jet plain discovered in the heart of the desert is believed ______ a UFO and _______down for reasons still mysterious.
Since 1949, the people’s living standard _______, causing a big _______ in population.
Going on a trip into___ space must be quite____ exciting experience.
To our anger, many poverty-stricken counties build luxurious office buildings instead of money to improve the miserable conditions of local schools.
The ______, I think, he drew from his simple experiment is not scientific.
—You know I dropped medicine and physics. —You made a right decision.