headfirst

头朝下地、头先著地地

He slipped on the ice and fell headfirst into the snow.

他在冰上滑倒，头朝下摔进雪堆里。

贸然地、鲁莽地、一头栽入地

She jumped headfirst into the new job without asking questions.

她什么都没问就一头栽进这份新工作。

头朝下的、头先入水的

His headfirst dive into the shallow pool looked dangerous.

他头朝下跳进浅水池的动作看起来很危险。