(a) being active or lively 活动性; 活力.
(b) busy or energetic action 繁忙的或充满活力的活动
*The house has been full of activity all day. 房子 整天都很热闹.
2 [C esp pl 尤作复数] specific thing or things done; action; occupation 所做的事情; 活动; 工作; 消遣
*outdoor, recreational, sporting, classroom activities 户外, 娱乐, 体育, 课堂活动
* Her activities include tennis and painting. 她的活动包括打网球和绘画.
* Sailing is an activity I much enjoy. 帆船运动是我非常喜爱的活动.
[C usually plural]
something that you do because you enjoy it
leisure/recreation/outdoor/cultural etc activities
outdoor activities such as hiking or climbing
[U and C]
things that people do in order to achieve a particular aim
political/economic/business etc activity
Everyone is free to engage in peaceful political activity.
criminal/terrorist/illegal etc activity
a situation in which a lot of things are happening or a lot of things are being done
the noise and activity of the city
There's an amazing level of activity in the town centre currently.
Regular physical activity helps to control your weight.
1. While active, child-bearing age women are most likely to have low iron stores, he notes, "Men are not safe, especially if they don't eat meat and have a high level of physical activity." 他还指出，虽然积极锻炼的育龄妇女最有可能铁离子储量低，"但男性也并非不缺铁，尤其是在他们不吃肉类而又从事高强度的体力活动的情况下。"
2. When research into cloning is resumed, human cloning should remain a research activity for an extended period. 当克隆研究重新开始时，克隆人类应该仍然是一项历时长久的研究活动。
3. The unconscious is certainly the source of instinctive activity. But in creative thought the unconscious is responsible for the production of new organized forms from relatively disorganized elements. 潜意识无疑是本能活动的源泉。不过，在创造性思维过程中，正是潜意识使得相对无序的成分变成新的有序形式。
4. The future? Bosses could measure brain activity to learn worker quality. 那么未来会是个什么样子呢？老板可以通过测量大脑活动情况来了解工人的素质。
5. The boys of average ability and the gifted girls showed strong activity on both sides of their brains as they thought about the puzzle. 智力一般的男孩与天资好的女孩在解题时脑子的两半球都活跃。
6. There was a sudden drop in activity in the left side of the brain — the side most involved in language — and an exaggerated reaction on the right, the side strongest at thinking about the location of objects. 他们的左半脑 -- 与语言能力相关的那一半 -- 的活动急剧下降，而右半脑，擅长思考物体方位的那一半，却做出强烈的反应。
7. Numerous studies show that children who engage in regular physical activity do better in school than their inactive classmates. 许多研究表明，经常进行体育锻炼的孩子，在学业上比他们那些不活动的同学优秀。
8. He could predict their performance from the strength of the brain's electrical activity measured through the head. 通过所测量到的他们头部脑电波活动的强度，他能够预测他们的成绩。
9. His studies with rats have demonstrated two primary effects of activity: vigorous physical exercise provides the brain with more fuel, and skill-based exercise increases the formation of connections in the brain, which, according to the proposals of 他对老鼠的研究已经表明运动具有两大功效：强力体育运动给大脑提供更多的燃料，而技巧性的运动则增强大脑神经的联结。依照某些科学家的见解，这种联结能使大脑更好地处理信息。
10. During a single crucial three-week period during our teenage years, chemical activity in the brain is cut in half. 我们的青少年阶段有一个为期三周的关键时期，此时脑部的化学反应活动一分为二。