单项选择题
A. 心理学家已经研究人们经历上的变化,特别是当他们离开农村进入城市的时候。 B. 当心理学家离开农村进入城市的时候,他们研究了人们经历上的变化。 C. 心理学家们一直在研究人们在离开农村进入到城市时所经历的变化。 D. 心理学家,从农村到城市,一直在研究人们所经历的各种变化。
A.Cambridge has a long history. B.The town was built before the university. C.Many students lacked money, so colleges were set up then. D.It was cheaper for students to live in college than in lodgings.
A.crime rate B.disadvantage of living in cities C.advantage of living in cities D.constant threat