In line 97, filling that gap means
A. covering the space between the sun and the Earth
B. adding to our knowledge about objects that could strike the Earth
C. measuring the gap between the ground and a falling object
D. completing our understanding of why objects explode above the Earth
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According to the passage, what are astronomers doing so we are better prepared for a possible asteroid strike?
A. building early-warning systems
B. equipping rockets with nuclear bombs
C. compiling a list of asteroids
D. studying the craters created by asteroids
Which method of deflection wouldn't work well ona rotating asteroid?
A. exploding a nuclear bomb nearby
B. hitting it with a spacecraft
C. pulling it using gravity
D. landing on it and pushing it
What might change the course of Apophis so that it hitsthe Earth within the next 30 years
A. Its own gravity
B. a spacecraft's gravity
C. the Earth's gravity
D. a comet's gravity
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