without warning
without question
without delay
without (a) doubt
with the exception of
under the impression that
under / in the circumstances
to the / this day
to / on the contrary
out of the question
out of practice
on the strength of
on the off-chance
on the brink of
on impulse
on fire
on edge
on / behind schedule
of the opinion
in theory
in the mood for
in short
in other words
in favor of
in due course
in confidence
in command of
in brief
in all likelihood
in addition to
in a sense
in a flash
out of touch (with)
out of one’s element
in (no) time
for lack of
for a change
by virtue of
by definition
by all accounts
by (any) chance
behind the scenes
at the same time
at the mercy of
at most
at fault
at face value
at any rate
at any cost
at all costs
at a standstill
at a price
at a moment’s notice
at a loss
at a glance
on the double
 in the end
from the outset
at (the) risk (of)