a man of letters=a learned man
He is a man of letters of this village.
a bed of roses=a bed of flowers
Life is not a bed of roses.
a black sheep=a bad person
He is a black sheep of the family.
at home in=expert
Mohammad is at home in all subjects.
He is above all a doctor.
along with sb/sth=in addition to sth/sb
He lost his money along with his fame.
an open secret=a secret that is known to all
The matter is now an open secret that he killed him.
again and again=time and again
I told him not to do it but he is doing it again and again.
all on (of) a sudden=quickly and unexpectedly
The police attacked the robber all of a sudden.
at every step=at every moment/stage
We should be aware at every step of our life.
at length=after a long time
I saw him at length.
all the while =always
He grumbles to my ear all the while.
at any cost=in any way
I have to pass in the examination at any cost.
at all events=whatever happened
We will reach there in time at all events.
at dead of night=in the quietest part of the night
The robbers came to house at dead of night.