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1·In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation worldwide has decreased significantly.

在《清洁空气法案》强制要求美国使用无铅气体的二十年里，铅在世界范围内的累积量显著下降。

2·All new cars, too, are built so that they can only take unleaded gas.

同时，所有的新型车都只能加无铅汽油。

3·In the twenty years that the Clean Air Act has mandated unleaded gas use in the United States, the lead accumulation world-wide has decreased significantly.

在过去的20年里《空气洁净法案》要求在美国只能使用无铅汽油，因此世界范围内的铅沉积有了显著下降。

4·My gas tank needs to be filled with unleaded.

我的油槽必须加满无铅汽油。

5·Drivers shelled out less at the pump as gas prices fell again, down almost a penny from Monday to a national average of about $2.74 a gallon for unleaded regular.

由于汽油的价格下降，司机在加油站支付的减少，从星期一下下降接近一美分到国家平均水平大约2.74美元一加仑——对于常规无铅汽油。

6·My gas tank needs to be filled with unleaded.

请加满不含铅的汽油，并检查一下机油。