英和和英

not often

not many times

never again

never again

a normal period without any major incidents

not even once

the waiting period before the arrival of a certain time

I am pressed for time.

being unprecedented

He often comes to my house, though he has no business with me.

at no time

never except when

once―（したことがあるか）―ever （?）―（したことが無い）―never

occasionally

occasionally

now and then or here and there

The hours are irregular.

ever so many times

once or twice

once or twice

once or twice

once or twice

The precise time is not mentioned.

on occasion―occasionally

once

Once in a while everything goes wrong.

either once or twice

Hardly any time

as often as one likes

as often as one likes