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。
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。
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.