Many children like watching TV．It's very interesting and they can see a lot and know many things about other people．They can also learn from the radio．But they can learn easily with TV．Why? Because they can hear and watch at the same time．But they can't watch anything from the radio(收音机)．TV helps to open children's mind(思想)．They can find better ways to do things．

    Many children watch TV only on Saturday and Sunday nights．They are busy from Monday to Friday．But some children watch TV every night．They go to bed very late．It's not good for their eyes and health.

如图是分别表示甲、乙、丙、丁四种物质熔化或凝固规律的图线，下列说法正确的是（　　）

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