All at once phrase
At the same time.
Friendship and rivalry between the two boys developed all at once.
Don't all question all at once! One by one, please.
Suddenly and unexpectedly.
All at once it poured, so I borrowed James's umbrella.
All at once John appeared at the door, which startled me.
Impulsively or suddenly
To rise fast and suddenly, then fall quickly and dramatically.
To kill someone in a very quick or abrupt way
May mắn bất ngờ xảy ra.
To be very wet
Because of forgetting bringing an umbrella, I look like a drowned rat when it rains.