Because adjective (relative) clauses are very useful in
giving descriptive information in both speaking and
writing, they are something you will hear, see, and want
to use in English. You should, however, be careful in
using them. Be especially careful not to make these
common mistakes:

1. Don't confuse who and whom.

The relative pronouns who and whom are often
especially confusing for learners of English--particularly
since who often replaces whom in non-formal speaking
and writing.

Remember that in formal speaking and writing, who is
for subjects and whom is for objects. Also remember
that in non-formal speaking and writing, who can be
used for whom, but whom cannot be used for who*.

Examples

Bob is the person who is talking. (correct)

Bob is the person whom is talking. (incorrect)

Bob is the person to whom we were listening.
(correct--formal)

Bob is the person whom we were listening to.
(correct--less formal)

Bob is the person who we were listening to.
(correct--non-formal)

* Some people feel that whom "sounds better" than
who because it is more formal. Remember that whom
only sounds better if it is used correctly!!

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2. Be careful with word order.

Word order is often a problem with adjective clauses
if a sentence has other modifiers after the noun phrase
that is being described.

Remember that in clear speaking and writing (especially
in clear writing), the adjective clause comes just after
the noun phrase that it modifies. It can be a problem,
however, to know where to put the adjective clause
and where to put other modifiers. It may, in fact, be
necessary to write sentences with adjective clauses
and other modifiers (particularly more than one
adjective clause) in a different way in order to make
them clear.

Examples

Judy is the girl who has blond hair who is standing
beside Bill. (confusing)

Judy is the girl who is standing beside Bill who has
blond hair. (confusing)

Judy is the girl with blond hair who is standing
beside Bill. (confusing)

Judy is the girl who is standing beside Bill with
blond hair. (confusing)

Judy is the blond-haired girl who is standing beside
Bill. (rewritten--and clear)

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Jack is a person who is in my class who(m) I like
a lot. (confusing)

Jack is a person who is in my class I like a lot.
(confusing, awkward)

Jack is a person who(m) I like a lot who is in
my class. (confusing)

Jack is a person I like a lot who is in my class.
(confusing)

I like Jack, who is in my class, a lot.
(rewritten--and clear)

________________

Ana has two children whose names are Felipe and
Luz who are in junior high school. (confusing, awkward)

Ana has two children who are in junior high school
whose names are Felipe and Luz. (confusing, awkward)

Ana has two children, Felipe and Luz, who are in
junior high school. (rewritten--and clear)