他们想在有风的日子阻止沙子，并使空气清洁。
They want to stop the sand on windy days and make the air clean.
由内而外的呼吸过滤器呼吸孔关闭，使空气清洁和干燥。
From the inside Breath hole closed by Breath filter to make air clean and dry.
美国人在其后数十年中取得的进步使我们的孩子更加健康，我们的水和空气更加清洁，我们的家园更适于居住。
What Americans achieved in the decades that followed has made our children healthier, our water and air cleaner, and our planet more livable.
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