质子核磁共振谱（PMR）是研究有机物结构的有力手段之一．在所研究的化合物分子中，每一结构中的等性氢原子在PMR谱中都给出了相应的峰（信号）．谱中的强度与结构中的H原子数成正比．例如：乙醛的结构为CH₃CHO，在PMR谱中有两个信号峰，其强度之比为3：1．

H₂O和CS₂分子中的原子都达到稳定结构．

    On Thursday evening, Jack goes to bed early. Then he sees a rabbit. Jack doesn't know1it is from. He doesn't have a pet rabbit at home.     “Come on,” says the rabbit. “Let's go to town!” “You can2?” Jack asks. “Yes,” the rabbit answers. “Come 3me.” Then the rabbit goes out of the4Jack goes with it.

    They get to a zoo. In the zoo, a(n)5 is playing the guitar under a tree. “Let's dance!” says the rabbit. Jack 6with the rabbit. And he sees the moon is dancing, too. Jack wants to tell the rabbit about this,7he can't find it. And he doesn't see the zoo or the lion. He sees his8! “Jack, get up! You have to go to school!” says his mom. Jack smiles and he can't wait to9his mom about the dream. It's so10.