将变形虫切割成不等的两部分，有核部分继续生活，无核部分都死亡，将变形虫的细胞核取出后，两部分死亡；将变形虫的细胞核取出，一定时间后再植入细胞核，细胞能够正常生活。该实验不能得出的结论是(　　)

根据短文内容回答下列问题。

    A poor farmer had a friend who was famous for the wonderful apple trees he grew.

    One day, his friend gave the farmer a young apple tree and told him to plant it. The farmer was pleased with the gift, but he did not know where to plant it.

    He was afraid that if he planted the tree near the road, strangers would steal the fruit. If he planted the tree in one of his fields, his neighbours would come at night and steal some of the apples. If he planted the tree near his house, his children would take the fruit. Finally he planted the tree in his woods. But without sunlight and good soil(土壤), the tree soon died.

    Later the friend asked the farmer why he had planted the tree in such a poor place. "What's the difference?" the farmer said angrily and then told what he had thought.

    "Yes, "said the friend, "but at least someone could have enjoyed the fruit. Now you not only have robbed everyone of the fruit, but also you have destroyed(毁掉) a good apple tree!"

胎儿在母体内的生长发育需要营养物质和排出废物，胎儿与母体之间进行物质交换的器官是（   ）

    A rainforest is an area____(cover) by tall trees with the total high rainfall spreading quite equally through the year. Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate.____the forest cover, these areas would reflect more heat into the atmosphere,____ (warm) the rest of the world. Losing the rainforests may also influence wind and rainfall patterns, potentially causing certain natural disasters all over the world.

    In the past hundred years, humans ____(begin) destroying rainforests in search of three major resources: land for crops, wood for paper and other products, land for raising farm ____ (animal). This action affects the environment as a whole. For example, a lot of carbon dioxide in the air comes from burning the rainforests. People____(obvious) have a need for the resources we gain from cutting trees,____ we will suffer much more than we will benefit.

    Rainforests are often called the world's drug store. More than 25% of the medicines we use today come from plants in rainforests. However, fewer than 1% of rainforest plants have been examined for their ____(medicine) value. It is extremely likely ____our best chance to cure diseases ____(lie) somewhere in the world's shrinking rainforests.