把下列句子中的从句改为不定式短语。
1. There are still a lot of difficulties we have to overcome.
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2. Before the machines leave the factory, there is a series of tests that must be passed.
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3. At the end of the speech he expressed the desire that he should come and work in China someday.
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4. They signed an agreement that they should expand the trade between the two countries.
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5. The commander gave orders that we should cross the river.
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6. She was excited when she heard the news.
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7. I'm glad I have seen your mother.
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8. The mother was pleased when she saw her son doing so well at school.
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9. He was very happy when he saw us so happy.
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10. They will be disappointed when they hear it.
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