How did the researchers carry out their study？
A. They studied the findings of several previous research projects.
B. They conduced a questionnaire with 411 pilots.
C. They collected data from the database at the Johns Hopkins University.
D. They analyzed the circumstances of the crashes involved.
A．evenB．the sameC．hardlyD．do
A. even
B. the same
C. hardly
D. do
A．factsB．livesC．natureD．world
A. facts
B. lives
C. nature
D. world
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