News Plus慢速英语:我国31个省制定污染治理目标 着重减少PM2.5浓度

重点讲解：
1. refer to
指的是；
eg. It can also refer to a conflict or disagreement, often involving violence.
这个词还可指冲突或不和，常涉及暴力行动。
eg. Twin deficits refer to budget deficit and trade deficit.
双赤字指预算赤字和外贸赤字。
2. as well as
除…之外；也；还；
eg. You must deposit 500 as well as the first month's rent.
你必须付500英镑押金及第一个月的租赁费。
eg. The child is lively as well as healthy.
这孩子既健康又活泼。
3. account for
（数量或比例上）占；
eg. Repeat order account for much of our business.
续订货占了我们生意的很大部分。
eg. Petrochemicals today account for one fourth of all the chemicals made, in ten years this amount is expected to double.
石油化工产品现在已占所有化学制品的四分之一，十年后预计这个数目还要加倍。