Nouns can be referred to with quem, que or o qual / a qual / os quais / as quais. Obviously only the last one can match in gender and number with the noun, because quem and que are invariable. O qual / a qual / os quais / as quais is mostly used after polysyllabic prepositions or after prepositions consisting of several words. In the case of monosyllabic prepositions there is a preference for que (in case that the object referred to is a thing or a person) or quem (in case that the object referred to is a person).
Sem and sob are the exception to this rule. Although this prepositions being monosyllabic qual / quais is used.Since there is an article in front of qual / quais the preposition can clash with an article. We should therefore remember what has been said in 4.1.1.
o
a
os
as
a
ao
à
aos
à
de
do
da
dos
das
em
no
na
nos
nas
por
pelo
pela
pelos
pelas
Ele
é
o
homem
pelo qual
todos
nós
temos
respeito.
He
is
a
man
for whom
all
we
have
respect.
He is the man respected by all of us.
Conhecimentos
sem os quais
não
se
consegue
viver.
Knowledge
without of it
not
somebody
achieve
to live
The kind of knowledge one can't live without.
Essa
é
a
perspectiva
sob a qual
a
relação
social
entre
trabalho
e
capital
é
concebida.
This
is
a
perspective
under which
a
relationship
social
between
work
an
capital
is
considered.
This is the perspective from which the social relationship between labour and capital is perceived.
A
equipa
contra a qual
ninguém
quer
jogar.
The
team
against which
nobody
wants
to play
Estavam
inscritos
32
pilotos
entre os quais
quatro
portugueses.
Were
enroled
32
pilots
between which
four
porutuguese.
32 pilotes were enroled, among them four Portuguese.
As
circunstâncias
entre
as quais
você
vive
determinam
sua
reputação.
The
conditions
between
which
you
live
determine
your
reputation.
The way you are perceived depend on the living conditions you are living in.
Uma
afirmação
contra a qual
os
pais
se
opuseram.
An
assertion
against which
the
parents
themselves
opposed.
An assertion not accepted by the parents.
Since a qual / o qual / as quais / os quais matches in gender and number with the noun, it is possible, at least if the referred object is unambiguous, to avoid ambiguity using a qual / o qual / as quais / os quais instead of que / quem.
O filho da Maria,
que
estuda frances, esta na Francia agora.
1) The son of Maria,
who
studies French, is in now in France. => The son of Maria studies French.
2) The son of Maria
who
studies French, is in now in France. => Maria studies French.
=> It is unclear whether que rerfers to Maria or her son.
We can avoid this ambiguity by using o qual / a qual / os quais / as quais, because the son of Maria is masculine and Maria feminine.
O filho da Maria,
a qual
estuda frances, esta na Francia agora.
Maria studies French.
O filho da Maria,
o qual
estuda frances, esta na Francia agora.
The son of Maria studies French.
Obviously that only works if the nouns differ in gender or number.
Without any preposition qual can only be used in nonrestrictive relative clauses.
correct:
Estavas à procura do livro que encontrei.
wrong:
Estavas à procura do livro o qual encontrei.
Furthermore there is a strong preference for que in case of monosyllabic prepositions. In case of polysyllabic prepositions there is a preference for qual. Sem and sob are exceptions to this rule.
