即使使用了安全带时，孩子仍需要很多的保护，例如调整儿童之间的距离；保持安全带发挥作用；并保证清洁。
Even when in use, they require a lot of maintenance—to adjust them from child to child, to keep them in good working order and to keep them clean.
为了清洁空气，加利福尼亚规定所有船只，在驶进距离岸边44公里范围内时，必须使用低含硫量燃料。美国各州中只有加州是这么规定的。
To clean up the air, California is the only state in the U.S. to require all ships to use low-sulfur fuel when they are within 44 kilometers of the shore.
在国际海洋组织的规定下，从2012年起，所有船只在进入距离北美洲海岸370公里水域内时，必须使用清洁柴油。
Starting in 2012, under the International Maritime Organization's regulations, all ships within 370 kilometers of North America will have to use cleaner diesel fuel.
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