20'

In some developing countries，the cost of living is increasing faster than the family income.
在一些发展中国家，生活成本的增长速度超过了家庭收入。

the cost of living 生活成本
family income 家庭收入

15'

If you buy this book，the other one is free of charge.
如果你买这本书，另一半书免费。

free of charge 免费

11'

Luxury cars are status symbols.
豪车是身份地位的象征。

status symbols 身份地位的象征