1 . 单句改错
（1）The earth is round, that circles round the sun.
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（2）He had two sons, both of them are college students.
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（3）He failed in the exam, as made his father very angry.
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（4）I may have to work late, in that case I'll phone you.
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（5）He visited the Great Wall again, there he went two years ago.
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