once a week是频率副词,表示的是一种不断重复的行为频度,往往放在句子中间，实义动词之前，非实义动词之后，在否定句中，有的频度副词位于否定词之前或之后均可，而有的频度副词则必须位于否定词之后，还有的频度副词却必须要位于否定词之前。

once a week是频率副词吗

频率副词等级

all the time 100%；

almost，always 90%；

generally，usually 80%；

often，frequently 60-70%；

as often as not 40-50%；

sometimes，at times 20-30%；

occasionally，from time to time 10%；

hardly，seldom，rarely 5%；

never 0%。

3、频率副词用在be动词后

He was always late.他以前经常迟到。

4、频率副词用在实意动词前

My father usually walks home.我的父亲经常步行回家。

once a week造句

1、How many skateboard classes once a week?

2、Occurring, appearing, or done once a week or every week.

3、Go once a week if you can.

4、Lung cells were replaced once a week.

5、She does the aerobics once a week.

6、What you should do: Run Yasso 800s once a week.

7、We used go to the movies about once a week.

8、Hence clean the ears once a week with cotton buds.

9、They also check for diseases or pests once a week.

10、Proofread the English Ad once a week by Email.