Question

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in 2011, a research satellite was nearing the end of its operational life and due to fall back to earth. scientists were questioned about whether a six - ton (5.4 - metric - ton) object falling to earth from space could be dangerous. the scientists were not too concerned. the chances of satellites striking inhabited areas are very small. that is because most of the planet is covered in water. on land, there are vast regions of emptiness.
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space objects are usually ______.
a harmless
b stationary
c plentiful
d explosive

Explanation:

The context is about space objects falling to Earth. The scientists were not too concerned because the chance of hitting inhabited areas is small. So space objects are usually harmless (A) as the danger of harming inhabited areas is low. "Stationary" (B) is about movement, "plentiful" (C) about quantity, "explosive" (D) about explosion, which don't fit the context of low danger.

Answer:

A. harmless