n.援兵;救兵;后援;援军;
例句:
Reinforcements arrived too late.
增援部队来得太迟了.
Only about a third of the reinforcements will be regular troops.
增援部队中仅有约1/3是常备军。
Reinforcements were sent across the river under cover of darkness.
在夜幕的掩护下,增援力量被派到了河的对岸.