按要求变换句子。
（1）That is a pen.(变为复数)
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（2）They’re from Canada.(变为一般疑问句)
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（3）There are 45 students in the classroom.(根据答句提出问句)
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（4）Is your father at home?(作否定回答)
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（5）Where are your books?(根据实际情况作答)
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