句型转换。

1. I think we will go on a trip to the ocean. (否定句)

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2. I will visit my aunt and uncle. (同义句)

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3. What does this cloud look like? (同义句)

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4. I wear a swimsuit to go swimming. (对划线部分提问)

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5. There are some new leaves on the tree. (否定句)

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6. There are some flowers and grass under the tree. (对划线部分提问)

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潜伏性感染是指（）。

A.病原体侵入人体后，只引起轻微症状

B.病原体侵入人体，引起免疫反应，不出现症状

C.病原体侵入人体发生免疫反应，不出现症状

D.病原体与人体保持永久平衡，不出现症状

E.病原体与人体相互作用，保持暂时平衡，当人体防御机能减弱时，可引起疾病