It's a pretty newinvention, only around since 1947 when a Michigan woman asked Edward Lowe if he knew ofan alternative to the sand or ash that she had been using.

猫砂是一个很棒的发明，其起源可以追溯到1947年，当时一位密歇根州妇女向爱德华·劳询问是否知道某种沙子或者灰可以用来清洁猫的粪便。

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Not only are we being asked to look out for ash, we are also being urged to identify ones that might be infected.

BBC: The heartbreak of watching the slow death of ash trees

Walkers in the Yorkshire Dales are being asked to take precautions to prevent the spread of a disease that is threatening millions of ash trees.

BBC: Ash dieback disease: Walkers urged to help prevent spread