plunge into
1．begin work or an activity eagerly or abruptly投入（行动）
She plunged into her new assignment the moment she got it．她一接到新工作就立即投入了进去。
When the subject was brought up，everybody plunged into the discussion．问题一提出，大家都投入了讨论。
2．throw oneself into some state 陷入
She switched off the light and plunged the room into darkness．她把灯关了，房间一下子就黑暗了。
He was plunged into despair by the terrible news．听到可怕的消息后他陷入了绝望中。
They plunged deeper into debt．他们负债更多了。