题目

阅读理解 Thelight from the campfire brightened the darkness, but it could not prevent thedamp cold of Dennis's Swamp (沼泽地) creeping into their bones. It was astrange place. Martin and Tom wished that they had not accepted Jack's dare.They liked camping, but not near this swamp. So, Martin asked as they satwatching the hot coals. How did this place get its name? Are you sure you want to hear it? It's ascary story, warned Jack. Of course! cried out Tom. Ifthere were anything to be scared of, you wouldn't have chosen this place! Ok, but don't say I didn't warnyou, said Jack, and he bega10．已知一个碳原子的质量是A千克，一个氧原子的质量是B千克，则氧原子的相对原子质量为$\frac{12B}{A}$．