YOU SAID:

when i go to the store i have to buy milk

INTO JAPANESE

私は店に行くとき私は牛乳を買わなければならない

BACK INTO ENGLISH

When I go to the store I have to buy milk

INTO JAPANESE

私は店に行くとき私は牛乳を買わなければならない

BACK INTO ENGLISH

When I go to the store I have to buy milk