always：
Peter is always getting into trouble.
彼得总是遇到麻烦。
usually：
They usually get their work done on time.
他们通常按时完成工作。
frequently：
My sister frequently goes shopping in Seattle.
我妹妹经常去西雅图购物。
rarely：
They rarely ask questions about the homework.
关于家庭作业他们很少提问。
频率由高到低：
always：总是
He always does his homework.
他总是完成作业。
usually：通常
They usually complete the work on time.
他们通常按时完成工作。
often：经常
I often watch movies online.
我经常在网上看电影。
sometimes：有时候
Jack sometimes comes over for dinner.
杰克有时会过来吃饭。
occasionally：偶尔
She occasionally asks a question.
她偶尔会问一个问题。
rarely：很少
They rarely have any homework.
他们很少有作业要做。
never：从不
I never complain at work.
我在工作中从不抱怨。
那么，频率副词在句中应该放在什么位置呢?我们来看看下面的规则：
如果句子中有一个动词(例如没有助动词)，我们通常将副词放在句子的中间，即在主语之后，动词之前：
subject / adverb / verb / predicate
主语/副词/动词/ 谓语
Tom usually goes to work by car.
汤姆经常开车去上班。
Mary often asks me for help.
玛丽经常请我帮忙。
频率副词通常放在“be”动词之后：
subject /be verb / adverb / predicate
主语/be动词/副词/谓语
Tom is often late.
汤姆经常迟到。
Anne isn't usually sick.
安妮通常不怎么生病。
Peter isn't always right.
彼得并不总是对的。
