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
That didn't even make that much sense in English.