例句：
They also increase alertness and energy.
它们也能提高机敏性和精力。
It made some evolutionary sense, that state of alertness.
那种警觉的.状态会形成某种进化感。
Research has shown that the lavender scent increases alertness.
研究表明薰衣草香味会提高人的警惕性。
Do not assume that more sleep equals more energy and alertness.
但不要以为多睡就意味着精力充沛。