关于细胞的叙述，错误的是（　　）

“这不仅改变了美国过去在和平时期不参加美洲大陆以外任何军事集团的传统对外政策，而且标志着美国以欧洲为重点的全球战略部署业已初步完成。”这评论的是（   ）

过点 作一直线与椭圆 相交于A、B两点，若 点恰好为弦 的中点，则 所在直线的方程为____．

    Yuan Longping is one of China's most famous scientists. ____(work) the land to do his research, he considers himself a farmer. Indeed, his sunburnt face and arms and his slim, strong body are just like those of millions of Chinese farmers, ____ he has struggled for the past five decades. When he was young, he saw many people dying of ____ (hungry), which was a ____(disturb) problem in many parts of the countryside. Then, he devoted all his time and energy ____searching for a way to increase rice harvests without expanding ____ area of the fields. In 1973, he became the first agricultural pioneer in the world ____ (grow) rice that has a high output. Now, he remains ____(circulate) his knowledge in many less developed countries to increase their rice harvests. He is quite ____(satisfy) with his life. However, he doesn't care about being famous. He feels it gives him less freedom to do his research. In his view, spending money on himself or ____ (lead) a comfortable life means very little to him. He therefore gives much money to equip others for their research in agriculture.