填空题

A variety of gases trapped in the Earth’s atmosphere can ensure life on Earth because they are ______.

【参考答案】

balanced/in a delicate balance

<上一题目录下一题>

热门试题

填空题

______ is very important to the absorption of the rainfall.

填空题

Because of deforestation, we are losing many precious species to human beings, which may eventually lead to a loss of ______ on a large scale.