小陈在观察成熟叶肉细胞的亚显微结构照片后得出如下结论，其中错误的是(   )

下左图、下右图分别示意1700一2000年中国、美国、巴西和印度四国人口和耕地的变化状况。读图，1700一2000年，人均耕地面积明显呈“先增后减"变化态势的国家是(     )

探究绿叶在光下制造有机物的实验中：

①把盆栽的天竺葵放在黑暗处一昼夜．

D

    He Jiang, a postgraduate（研究生）in biology. will become the first Chinese student to give a speech in the commencement(毕业典礼)at Harvard University on May 26, 2016.

    Given the highest honor by the university, He Jiang, who was born in a small village in Hunan province, said, "People in China often believe that it's useless to study and children from the countryside cannot be successful in the future. However, I cannot agree with them. Education can change a person's life. I hope my experience can encourage the students from the countryside to spare no effort in study and make their dreams come true."

    Different from many other families in the village, his parents never thought about finding a job in big cities and leaving their two sons at home without their care. His father was strict about their studies. He and his younger brother studied at home while the other kids in the village played in the fields. Unlike his strict father, his mother took her sons' side when her husband scolded the boys. She preferred to sit with her sons when they studied rather than chat with other women in the village.

    Getting the chance to speak at the commencement is no accident. During his first days in Harvard, it was quite difficult for him to follow the professors in class and he was speechless in campus because of his poor English. Instead of giving up, He Jiang spent all his free time on English. He also made friends with natives to improve his speaking English. One year later, he had little difficulty in class and soon became one of the top students in his class. With the encouragement from Professor Diana Eck. He Jiang decided to apply(申请）for the chance to speak at the commencement.“Few Chinese students had applied before, but I wanted to have a try. I just want to realize my idea of letting more people hear the voice from China and telling them that China is not what it used to be." said He Jiang. After beating three students from Harvard Kennedy School in the third and final round, He Jiang made it to get the chance to speak at the commencement.

    He Jiang will go to Massachusetts Institute of Technology after graduating from Harvard.