前面加冠词the，例如：

1.Their mood is generally glum-and not just because of the pollution that has blighted China's capital over recent months, after what had been a glorious spring.他们大都心情郁闷，不仅仅是因为近几个月一直困扰中国首都的污染问题——在过了一个明媚的春天之后。

pollution是"污染"的意思，是不可数名词，前面只能加定冠词the