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When _________ to explain his mistake, the new employee cleared his throat nervously.

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Police are _____ significant progress in fighting computer crime.

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Saving _________ species from becoming extinct is crucial for our health and the future of our children.

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Our sources of energy will soon be __________ if we don't save them.

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Try to keep a balance _____ your spending and your earnings.

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15,589 species (7,266 animal species and 8,323 plant species) are now considered ______ risk ______ extinction.

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Many ________ groups now support putting a value on ecosystems.

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The giant panda's natural ________ is the bamboo forest. Giant pandas like to eat bamboo leaves.