headlong

他不做任何研究就贸然投资了自己的钱。

He invested his money ___headlong without any research.

他匆忙中不慎摔倒了，头朝下地滚下楼梯。

He tripped in haste and tumbled ___headlong down the stairs.

他不顾警告，头朝下跳进了冰冷的湖水中。

Ignoring warnings, he jumped ___headlong into the freezing lake.