You need the gas to create a lightness and a crispiness, and an airiness.

你需要气体来创造一种轻盈、清脆和通风的效果。

It was so long and so level that even the airiness of the buoyant youngster at whom it was directed began to lessen perceptibly, long before Emma began to talk.

它是如此之长和如此平坦，甚至在艾玛开始说话之前很久，它所指向的那个活泼的年轻人的空气就开始明显地减少了。