1. calm: not getting angry or upset, even in a difficult situation

例：

I was trying to sound calm even though I was very upset. （虽然我很生气，但是我尽量让语气保持平和。）

Everyone praised Douglas for the calm way in which he handled the situation. （人人都称赞道格拉斯在处理这个问题时的冷静表现。）

keep/stay calm

Keep calm and try not to panic. （冷静点，别怕！）

2. stay cool/keep cool: to stay calm and not show your emotions, especially when other people are getting excited or angry

例：

Sampras is the kind of player who always manages to stay cool, even under pressure. （即使压力重重，桑普拉斯依然可以保持冷静。）

keep your cool (=not become angry)

He managed to keep his cool and ignore her last comments. （他依然保持冷静，对她刚才的评论置若罔闻。）

补充：

She looks efficient and as cool as a cucumber. （她看起来工作很有效率，并且冷静沉稳。）

Outwardly she is cool, calm, and collected. （她看起来很冷静。）

3. keep your head: to manage to stay calm and to behave in a sensible way when something is likely to make you feel frightened or worried

例：

Paul's good at keeping his head in a crisis. （保罗在危机到来时总会保持冷静。）

They were looking for a coach who could stay enthusiastic and keep his head at the same time. （他们想找一个富有激情并且头脑冷静的教练。）

We need a candidate who can keep his or her head even when clients get aggressive. （我们要招的人需要有这样的素质：即使顾客很凶要吵架，我们的员工也能保持冷静，正确处理。）

keep a clear/cool/calm head

Keep a cool head. （保持冷静。）

Get to sleep early tonight - you'll need to keep a clear head tomorrow at the trial. （明天上庭需要要头脑清醒，今晚早点睡吧。）

补充：''keep your head''的反义词''lose your head'': to become unable to behave calmly or sensibly in a difficult or frightening situation

例：

You'll be OK as long as you don't lose your head and forget he's the real enemy. （只要你头脑清醒，别忘了他是你真正的敌人，一切都会没事。）

4. composed: in control of your emotions so that you look and feel calm in a difficult or upsetting situation

例：

I could see that she was angry but trying to remain composed. （我知道她很生气，但是竭力保持冷静。）

It was several minutes before he felt composed enough to speak to anyone. （他冷静了几分钟，才能开口说话。）

He appeared very composed despite the stress he was under. （尽管压力重重，他仍显得非常冷静。）

5. presence of mind: the ability to stay calm that makes someone able to do the right thing immediately even in a dangerous or difficult situation

例：

His presence of mind prevented a serious accident. （他头脑冷静，将一场严重的事故化解了。）

presence of mind to do something

I'm still amazed that a terrified 19-year-old would have the presence of mind to reason with her kidnapper. （一个19岁的孩子被绑架了，还能头脑冷静地跟绑匪分析形势，我真是难以置信。）

6. unfazed/not fazed: calm in a difficult situation, especially one in which someone is trying to confuse or upset you

备注：''unfazed/not fazed''常用于非正式的场合。

例：

Barton seemed unfazed by the accusations of corruption. （巴顿被控贪污，但看起来还很镇定。）

A few traders are concerned by the recent drop in the stock market, but most are not fazed. （最近股票下跌，一些人很发愁，但大部分人很镇定。）

7. level-headed: able to behave sensibly, think clearly, and remain calm, even in a difficult situation

例：

A good pilot needs to be calm and level-headed. （一个好飞行员要保持头脑冷静。）

He had a level-headed approach to financial matters. （处理财政问题，他头脑冷静。）