前几天看了一篇文章，标题叫 Why TAL Education Group Stock Jumped 16% in February （《为什么好未来教育集团的股价 2 月份飙升 16%》）。文章写道：
What happened
Shares of Chinese after-school tutoring services specialist TAL Education Group (NYSE: TAL) jumped 15.9% last month.
So what
TAL stock continued in its recent upward, if volatile, trend during the month of February after the company released another impressive earnings report on Jan. 25. In TAL's fiscal third quarter of 2018, which ended Nov. 30, 2017, revenue soared 66.3% to $433.3 million versus the comparable prior-year quarter. Operating income more than doubled to $44.6 million. While selling and marketing costs rose roughly in line with revenue, the company's general and administrative expenses expanded at a slightly slower rate, rising by nearly 48% during the third quarter. Thus, TAL was able to achieve a bit of operating leverage, which resulted in the higher operating income.
文中这句话，再次引起了我这个英语老师的注意：
TAL stock continued in its recent upward, if volatile, trend during the month of February after the company released another impressive earnings report on Jan. 25.
其中的 if volatile ，到底是什么意思呢？接下来我会跟大家分享一下 if 这个词的用法和意思。
全文大约1400字，参考阅读时间7分钟。
[初阶用法]
这三个用法，中学老师基本上都讲到，我不做赘述。
1. 引导条件状语从句，表“如果”：
<If you have a complaint, write to the director.> 如果你有不满，直接给主任写信吧。
2. 引导虚拟语气条件句：
<If you hadn't been on the phone 10 minutes ago, you wouldn't have missed the awesome goal.> 如果你 10 分钟之前没有在打电话，你就不会错过这个超赞的进球。
3. 引导名词从句，表“是否”，但需是需要注意下面的细节：
1）if 引导的名词从句，只能当宾语
<I am wondering if you would like to go to the concert with me tonight.> 我不知道你是不是愿意和我今晚去听音乐会。
2）whether 引导的名词从句，可以当主语、表语和宾语
<It is not clear whether he has finished the job.> 他有没有完成工作还不清楚。
[中阶用法]
以下两种情况：
1. 状语从句主语与主句主语一致，且从句谓语是 be 动词；或者
2. 状语从句主语是 it 且从句谓语是 be 动词时
我们可以把从句的主语和谓语进行省略。
上面这段话太抽象了，不要看！直接感受一下例句，你会秒懂状语从句中的这种省略。这是英语语法进阶过程中很重要的一个细节。
<Don’t touch anything in the room unless (you are) told to do so.> 除非有人让你这么做，否则你不要触碰这个房间里的任何东西。
<Call the police, if (it is) necessary.> 如果有必要，就报警。
<Visit me when (it is) convenient.> 方便的时候来看我。
<If (it is) true, my mother will be SATisfied.> 如果这是真的，我妈妈就很满意了。
[高阶用法]
下面的内容，很多考生是没有掌握的，可是这也恰恰是 SAT 考试中，经常会出现的重要句型。
请注意，我在这里提及 SAT 考试，并不是说我一味偏重应试，真不是的，我最讨厌不提高实力妄求高分的做法了，一直关注我文章的朋友们，知道我这个立场的。
我之所以要提到 SAT 考试，其实是想表达：
SAT 的文章和考点，代表着书面英语的极高水平
代表着你去美国留学，想要如鱼得水、收获满满，所需要在英语上达到的程度
SAT 水准的文字，真的挺高端的
后接形容词、副词或者限定词，表示对于已经提及的情况的一种可能的否定。你可以尝试用 perhaps not 来替换 if 进行辅助理解。
<He has few, if any, friends.> or perhaps he doesn't have any friends at all
<He rarely, if ever, works out.> perhaps he never works out
<He has changed little, if at all, since the last meeting.> perhaps he hasn't changed at all
<Her needs are just as important as yours, if not more so.> perhaps even more important than yours
<You started your test preparation and college application process too late, making it difficult, if not impossible, to achieve satisfactory results.> perhaps it is not possible for you to achieve satisfactory results
表示对比，相当于“尽管“，后接形容词或副词
<She is honest, if a little brutal.> 她是诚实的，尽管略暴力。
<The eldest son was highly intelligent, if somewhat lazy.> 大儿子很聪明，尽管有点懒。
以上的两种用法在正式书面英语中是非常常见的，能够让表达更加简洁、清晰。
相信通过上面的解析，大家一定掌握了这种用法。最后，让我们回到文章开头提到的新闻报道里的句子：
TAL stock continued in its recent upward, if volatile, trend during the month of February after the company released another impressive earnings report on Jan. 25.
请你翻译这句话，私信我 “TAL”获取参考答案。
感谢你的阅读。
