Qian Xuesen was born in Hangzhou, Zhejiang Province on December 11,1911. After his graduation from Shanghai Jiao Tong University in 1934, he ____(旅行) across the Pacific Ocean to the United States for further study. There he received his degrees. After he graduated, he became a teacher as well as a researcher. He worked ____(努力地) and became a famous scientist.

    He ____(返回) to China in 1955. He played an important role in science in China. He was honored as “The Father of China's Missiles(导弹)”. He is the  ____(骄傲) of the Chinese people. He died on ____(十月) 31, 2009 at the age of 98, but he is a man who ____ (仍然)encourages Chinese young people. His love to his country was expressed in his saying, “My career(事业), my ____(成功) is in China and my destination is in China!” When someone said he could make much more money if he stayed in ____ (美国), he laughed and said, “My family name is Qian, but I don't like qian.”

不等式$\frac{x-3}{x+2}<0$的解集是　　　　　　　　　　　　　　　　　　（ 　　 ）

动物的学习行为受环境因素的影响，与遗传因素无关．

下列关于角的说法正确的个数是(    )

①角是由两条有公共端点的射线组成的图形；②角的边越长，角越大；③在角一边延长线上取一点D；④角可以看作由一条射线绕着它的端点旋转而形成的图形.