“on the ball”是英语中常用的习语，核心语义为“机灵的、反应快的、做事能力强的、警觉的、精明干练的、全神贯注的”，相当于alert and efficient，强调人对事物的敏锐感知、高效应对能力及专注度，可用于形容人在工作、学习、社交等多种场景中的良好状态，引申为形容一个人注意力集中、反应敏捷、做事靠谱。反义词是"off the ball"，意思是走神、不在状态。如：
She is really on the ball.
她很机灵。
If you don't get on the ball, you'll fail.
若你不打起精神，就会失败。
(放在系动词后面：比如get，feel, stay, keep等词，强调保持某种状态)
He noticed I was upset immediately and brought my favorite dessert—he’s so on the ball when it comes to caring for me.
他立马察觉到我不开心，还买了我最爱的甜点——在照顾我这件事上，他真的很细心机灵。
My girlfriend remembered our first date details even after three years; she’s always on the ball with things that matter to us.
即使过了三年，我女友还记得我们第一次约会的细节，在关乎我们的事情上她总是很上心机敏。
When planning our anniversary trip, he considered all my preferences perfectly—he’s really on the ball about our relationship.
规划周年旅行时，他把我的所有喜好都考虑到了，在维系我们的感情上他确实很精明周到。
After 20 years of marriage, my husband is still on the ball about my little habits, like how I take my coffee.
结婚20年，我丈夫对我的小习惯依然很上心，比如我喝咖啡的喜好。
You can always count on Lisa to help when you’re in trouble—she’s so on the ball and reliable.
你有困难时总能指望莉萨帮忙，她既机灵又可靠。
You need to be on the ball in the meeting, the boss might ask questions anytime.
开会时你可得注意力集中点，老板可能会随时提问
With so many intelligent students, the teacher must always be on the ball.
班上有那么多聪明的学生，老师必须时刻保持机敏。
As a politician, you must be on the ball in the election to respond to public concerns timely.
作为政客，你在选举中必须保持警觉，及时回应公众关切。
That banker is really on the ball—he spotted the investment opportunity before anyone else.
那位银行家确实很精明，他比其他人先发现了这个投资机会。
The diplomat was on the ball during the negotiation and avoided several potential conflicts.
这位外交官在谈判中反应机敏，规避了多次潜在冲突。
The commander remained on the ball throughout the mission and adjusted the strategy promptly when the situation changed.
指挥官在整个任务中始终保持警觉，形势变化时及时调整了策略。
Look, who's to say everything I do is 100% on the ball? 《欢乐合唱团》
那个，谁说我做的每件事都百分百靠谱机灵呢？
