Instead of trenching them into the foundation below the slabs, they reduced  the thickness of the concrete to make room for the drains.

他们没有将它们挖到板下方的地基中，而是减少了混凝土的厚度， 为排水沟腾出空间。

A 1987 agreement called the Montreal Protocol banned a series of chemicals — mainly used in refrigerants and aerosols — believed to have reduced the thickness of the ozone layer.

1987 年签署的《蒙特利尔议定书》禁止使用一系列化学物质——主要用于制冷剂和气雾剂——据信这些化学物质减小了臭氧层的厚度。

A 1987 agreement called the Montreal Protocol banned a series of chemicals – mainly used in refrigerants and aerosols – believed to have reduced the thickness of the ozone layer.

1987年签署的《蒙特利尔议定书》禁止使用一系列化学物质——主要用于制冷剂和气雾剂——据信这些化学物质减小了臭氧层的厚度。