If you redouble your efforts, you try much harder to achieve something. If something redoubles, it increases in volume or intensity.
例句
The president also called on nations to redouble their efforts to negotiate an international trade agreement...總統還呼吁各國就簽訂國際貿易協定加倍努力進行磋商。The applause redoubled.掌聲加倍熱烈。
英英詞典釋義
Adjective
1. become much greater in intensity or size or amount;
"we faced redoubled attacks from the enemy""despite our redoubled efforts"