题目内容：

阅读下面材料，在空白处填入适当的内容（1 个单词）或括号内单词的正确形式。

Dr. Yuan was born in Beijing in 1930. 1._________ he graduated from Southwest Agricultural College in 1953, he has given his life to 2.________ ( find ) ways to grow more and more rice.

As a young man, he saw the great need for increasing the rice output. At that time, famine was 3.________serious problem in many parts of the country. Dr. Yuan searched 4.________a way to increase rice harvests without expanding the area of fields. In 1950, Chinese farmers could only produce fifty million tons of rice. Last year, 5.________ , nearly two hundred million tons of rice6.________ ( produce ). These increased harvests mean that 22% of the 7.________ ( world ) people are fed from just 7% of the farmland in China. Dr. Yuan is now circulating his knowledge in India, Vietnam and other less developed countries 8.________ ( increase ) their rice harvests. Thanks to his research, the UN is trying to rid the world of 9.________ ( hungry ). Using his hybrid rice farmers are producing harvests twice 10.________ ( large ) than before.