In the example
above under 4b, the subject of the original sentence disappeared in the passive voice.
We usually leave out the subject of the original sentence in the passive sentence if it
is:
not
known
or not important
or obvious to everyone
Nevertheless, it is sometimes
necessary to identify the subject of the original sentence in order for the sentence to
make sense. If so, we use the preposition "by". For example:
Lightning
struck
my cousin
and he survived.
My cousin was struck
by lightning
and
survived.
Without the words "by
lightning", it could mean he was struck by a person or a car or …
Traffic delayed
me.
I
was delayed
by traffic.
Without the words "by
traffic", it could mean he was held up (robbed at gunpoint).
My grandmother
made
this
sweater.
This sweater
was made by
my grandmother.
Without the words "by my
grandmother", it would be a ridiculously obvious statement.
3
EXAMPLES