英語詞彙中有一類詞叫頻率副詞，通常修飾動詞，表示動作在一定時間內發生的次數，比如always, usually, often等詞彙，都可以解釋為「常常，總是」，但它們的用法卻不一樣，還有rarely和seldom，意思都可以解釋為很少，但是用法各異，需要認真加以區分。
今天介紹一組頻率副詞，這些頻度副詞所表示的動作頻率從高到低依次遞減，舉例如下，一起通過對比學習來區別這些單詞的用法。
01頻率副詞，頻率從高到低
always 始終，一直
usually 通常，往往
often 經常
sometimes有時（= on occasion, every now and then）
seldom很少（= rarely）
hardly ever 幾乎從不
never 從不
以上副詞與 be 動詞連用時，位置在 be 動詞之後；若與其他動詞連用時，位置在該動詞前。但是 usually 和sometimes 需置於句首。
02句型練習
1. wash your clothes （用How often 進行提問）
How often do you wash your clothes?
2. clean your room （用How often 進行提問）
How often do you clean your room?
3. wash the dishes （用How often 進行提問）
How often do you wash the dishes?
4. have a haircut （用How often 進行提問）
How often do you have a haircut?
5. go to the cinema （用How often 進行提問）
How often do you go to the cinema?
03改寫句子
1. He is late for school. (never) 用括號中的單詞或短語改寫句子。
He is never late for school.
2.It's very cold in winter. (usually) 用括號中的單詞或短語改寫句子。
It's usually very cold in winter.
3. They go to the park. (sometimes) 用括號中的單詞或短語改寫句子。
They sometimes go to the park.
4. My father washes the dishes. (seldom) 用括號中的單詞或短語改寫句子。
My father seldom washes the dishes.
5. Mom cooks for us. (always) 用括號中的單詞或短語改寫句子。
Mom always cooks for us.
6. They play football on Saturday afternoon. (Sometimes)
Sometimes they play football on Saturday afternoon.
他們有時在星期六下午踢足球。
04創設情境，學以致用
根據漢語完成對話。
Betty: __1__ （經常）do you play soccer, Tom?
Tom:I play soccer __2__ . （一周兩次）I __3__ （有時候）play baseball.
Betty: I like tennis. I __4__ （一直）play it with my friends.
Tom: I __5__ （從不）play tennis. I don't like it. Do you often play the piano?
Betty: I have to play the piano __6__ （每天）. I'm __7__ （一直）busy.
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