1. 关于位置
(1) 表示“经常”，通常放在行为动词之前，特殊动词（助动词、情态动词以及动词 be）之后。如：
He was often late for class. 他上课经常迟到。
We often go skating together. 我们常常一道去溜冰。
You must often come to see us. 你要常来看我们。
(2) 如果句子较短或为了强调，often可以放在句末。如：
You won’t see her often. 你不会常常看到她的。
如果句子较长或为了强调，often也可以放句首。如：
Often I miss breakfast and have an early lunch instead. 我常常不吃早餐，而吃一顿早午餐。
有时位于句首或句末是因为本身带有修饰语（如quite, very, so等）。如：
Quite often the phone rings when I’m in the bath. 电话经常在我洗澡时响。
When I was young, I used to play tennis very often. 我年轻时经常打网球。
(3) 有时often不是用于说明句子中的动词，而是用于说明整个句子的，此时也通用于句首。如：
Often, in the evening, we’d hear the sirens. 常常我们会在傍晚听到警报声。
Often, when he should have been doing something useful, he wasted his time drawing little pictures. 常常当他应当干些正经事时，他却浪费时间画小画。
(4) often置于句首时，有时其后可接倒装语序（但这并不是必需的）。如：
Often had she intended to speak of this. 她常想说及此事。
Often did we warn them not to do so. 我们曾多次警告过他们，不要这样做。
2. 关于时态
often通常与一般现在时或一般过去时连用，此外它还有以下用法值得注意：
(1) 与现在完成时连用，强调动词的一惯性和经常性。如：
You have often been told not to do that. 多次告诫过你别干那事。
I have often heard of him working hard. 我常听人说他刻苦用功。
(2) 与情态动词will连用，表示一种惯常的行为。如：
In fine weather, he will often sit in the sun for hours. 天气晴朗时，他常在阳光下坐好几个小时。
When you look at clouds they will often remind you of animals. 你观察云彩的时候，往往会联想起动物。
(3) 与情态动词would连用，表示过去惯常的行为。如：
When we were students we would often stay up all night. 我们当学生时，经常通宵不睡。
As he grew older, he would often talk about his war experiences. 他年岁大了，常常讲他的战争经历。
3. 在否定句中的位置
在否定句中，often可位于否定词not之前或之后。如：
They don’t often hold such parties. 他们不常开这样的晚会。
Statistics and surveys often don’t prove very much at all. 数据和调查常常证明不了什么。
4. as often as 用法
用于 as often as，有两个意思是，一是表示“与……一样次数多”。如：
He came as often as he could. 他尽可能常来。
二是起连词作用，相当于whenever，意为“每当”。如：
As often as I tried to ring him, the line was engaged. 每次我给他打电话都占线。
注意习语as often as not（通常，常常），也可说成more often than not。如：
When it’s foggy, the trains are late as often as not. 雾大时，火车往往晚点。