n.警戒；機敏
The other half of the brain stays awake at a low level of alertness. 另一半大腦在低水平警戒狀態(tài)下保持清醒。
They also increase alertness and energy. 它們也能提高機敏性和精力。
Without Alertness I'll be stupid. 沒有機敏那是愚蠢。
