social mobility的用法和样例：
例句
- This expansion of education has not brought about a similar increase in social mobility.
教育的扩张并未在社会流动性方面引起相似的增长。 - These obstacles have indeed suppressed productivity, incomes and social mobility in the countryside, and contributed to the widening gap between town and country.
这一制度极大地抑制了农村的生产力，收入和社会流动性的发展，进一步扩大了城乡差距。
