b1) The party, for which I am responsible for will be great.
c1) This is a person, of whom you should be aware.
d1) This is the woman, with whom I am in love.
a2) This is the table, on which the book lies.
b2) This was the idea, for which he died.
c2) This is the wall, of which he was talking earlier.
d2) This is the girl, with whom I had a fight.
Now the thing is: in the first group of sentences we have to use dont, in the second group we have to use lequel / laquelle / lesquels
/ lesquelles. How come? The first part uses phrases and compound verbs that belong definitely together. The second part, just use preposition without this fixed expression.
Examples
to be proud of =>
This is his son, of whom he is proud of.
to be responsible of =>
The party, for which I am responsible for will be great.
to be aware of =>
This is a person, of whom you should be aware.
In French many of these expressions are formed with the preposition de. In these cases the relative pronoun is dont.
Examples
avoir
peur de
C' est
une situation dont
j' ai peur.
to be afraid of
This is a situation, of which I am afraid.
avoir besoin de
C'est quelque chose
dont
j' ai besoin.
to need
This is something, that I need.
être amoureux
de
C' est la femme
dont je suis amoureux.
to be in love with
This is the woman with whom I am in love.
se souvenir de
C' est la seule
chose dont
je me souviens.
to remember
This is the only thing that I remember.
être content
de
C' est un résultat
dont je suis content.
to be content with
This is a result with which I am content.
se servir de
Voici le livre dont
je me suis servi.
to use
This is the book that I have used.
se méfier
de
C' est un homme
dont
il faut se méfier.
to mistrust
This is someone, whom I mistrust.
se nourrir de
Ce sont les fruits dont
ils se sont nourris.
to subsist on
These are the fruit on which they subsist.
être responsable
de
C' est l' organisation
dont
je suis responsable.
to be responsible for
This is the organisation for which I am responsible.
