YOU SAID:
Jack quickly crossed the road
INTO JAPANESE
ジャックはすぐに道路を横切った
BACK INTO ENGLISH
Jack crossed the road at once
INTO JAPANESE
ジャックは一度に道路を横切った
BACK INTO ENGLISH
Jack crossed the road at a time
INTO JAPANESE
ジャックは一度に道路を横切った
BACK INTO ENGLISH
Jack crossed the road at a time
That didn't even make that much sense in English.