1. 烧毁；烧光
If something burns up or if fire burns it up, it is completely destroyed by fire or strong heat.
2. 消耗；耗费
If something burns up fuel or energy, it uses it.
1. burn completely
be consumed or destroyed by fire
e.g. The hut burned down
The mountain of paper went up in flames
2. use up (energy)
e.g. burn off calories through vigorous exercise
3. burn brightly
e.g. Every star seemed to flare with new intensity