填空题

Porous clay is a kind of hard earth that can allow water to pass through and filter out the harmful organisms in it at the same time.

【参考答案】

Y

<上一题目录下一题>

热门试题

填空题

Potters for Peace is an non-government organization which receive funds from large businesses in the United States.

填空题

Potters for Peace has designed a low-cost system to purify dirty water, but it has not won governmental support.