按要求改写句子。

1. It's four o'clock. (就画线部分提问)

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2. I like swimming. (改为否定句)

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3. Does Jack like swimming? (作否定回答)

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4. 张琳晚上九点半睡觉. (译成英语)

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目前我国的用电负荷分为哪几类？