对下列生物或结构进行化学成分分析，最相似的是（　　）

 20世纪50～70年代，日本每年把全部财政预算的20%投入到教育领域，这说明第二次世界大战后日本经济迅速发展的一个重要原因是(     )

设N_A为阿伏加德罗常数的值．下列说法正确的是（   ）

根据材料内容，选择正确答案。

    One day a man found a cocoon(茧) of a butterfly in the forest. He sat there for several hours and watched the butterfly. Suddenly a small opening appeared, and the butterfly made its great effort to force its body through that little hole. Then it seemed to stop making any progress. It appeared as if it had gotten as far as it could and it could go no further.

    So the man decided to help the butterfly. He cut off the remaining bit of the cocoon so that the butterfly could come out easily. But to his surprise, the butterfly got a heavy body and very small wings when it came out of the cocoon.

    The man continued to watch the butterfly because he expected that the body would grow smaller at any moment and the wings would become larger and be able to fly. But neither happened! In fact, the butterfly spent the rest of its life crawling(爬) around with a heavy body and small wings. It was never able to fly.

    The man was in his kindness, but he did not understand the nature rules. Before the butterfly came out of the cocoon, fluid(流体) from its body must be forced into its wings, and then it would be ready for flying. It must have a hard struggle(拼搏) to get through the small opening to get its freedom from the cocoon.

    Sometimes struggles are exactly what we need in our life. If God allowed us to go through our life without any difficulties, it would make us fail. We would not be as strong as we could have been, we could never fly.