Time span + に + frequency
Say how often something happens
You'll be able to state how many times an action occurs within a given period.
父は一週間に三回走ります。
chichi wa isshuukan ni sankai hashirimasu.
What do you think this sentence means?
My father runs three times a week.
State how often something happens
A time span followed by に establishes the period within which a frequency is counted. It answers how often, rather than the clock time of one event.
一日に二回歯を磨きます。
ichinichi ni nikai ha o migakimasu.
I brush my teeth twice a day.
Form and use Time span + に + frequency
Use 一週間に三回 for three times a week and 一日に二回 for twice a day. Keep the period and the count distinct; 回 counts occasions, while 時間 measures duration.
一日に二回歯を磨きます。
ichinichi ni nikai ha o migakimasu.
I brush my teeth twice a day.
一年に一回京都へ行きます。
ichinen ni ikkai kyouto e ikimasu.
I go to Kyoto once a year.
この薬は一日に三回、食事の後で飲んでください。
kono kusuri wa ichinichi ni sankai, shokuji no ato de nonde kudasai.
Please take this medicine three times a day, after meals.
一か月に一回、髪を切りに行きます。
ikkagetsu ni ikkai, kami o kiri ni ikimasu.
I go to get my hair cut once a month.
このバスは一時間に二本来ます。
kono basu wa ichijikan ni nihon kimasu.
This bus comes twice an hour.
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