You use whereas to introduce a comment that contrasts with what is said in the main clause.
Benefits are linked to inflation, whereas they should be linked to the cost of living.
救济金与通货膨胀相关联,而它们其实应该与生活开支挂钩。
Whereas the population of working age increased by 1 million between 1981 and 1986, today it is barely growing.
从1981年到1986年,适龄工作人口增加了100万,可是如今却几乎没有任何增长。