Directions: Examine the following sentences and identify if the non-finite verb in each sentence is obligatory or optional.

Example: I can't stop working. working - obligatory

1. She begins searching for a stone.
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2. She could probably return in time to destroy the notes.
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3. I feel certain that I am going mad again.
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4. I feel we can't go through another of these terrible times.
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5. I begin to hear voices.
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6. I wanted to say that I owed happiness all the happiness of my life to you.
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7. I can't go on spoiling your life any longer.
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8. She may have tried to kill herself.
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9. She has flowers to buy.
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10. She has a party to give.
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