连词成句。  

1. on, like, chatting, my, with, friends, I, Internet, the    

2. he, exercise, does, about, hour, half, day, a, an, for    

3. are, table, the, juice, there, four, orange, on, cartons, of   

4. should, a, week, watch, than, hours, TV, five, you, less    

5. and, stay, right, exercise, healthy, doing, eating, food, you, help, can    

以下判断正确的是[ ]

A．只有在点燃或加热时可燃物才能燃烧

B．只要温度达到可燃物着火点可燃物就能燃烧

C．只有含碳元素的物质才能燃烧

D．只要使可燃物的温度降到着火点以下就能灭火