عاوز احول الجمله الى passive
He travelled to Cairo by car.
الدكتور جابها فى الامتحان ومعرفناش نحلها

travel is an intransitive verb so we cannot change it into passive

A car was used by him to travel to Cairo.

He was said to travel to Cairo by car.

The car was the means of transport which was used by him to travel to Cairo
He is (was) said to have travelled to Cairo by car
The car was used to travel to Cairo
or
for travelling to cairo

Intransitive Verbs aren't normally used in passive . so this sentence can't be turned in to passive but can be expressed in other forms that can be put in passive
It's said
A car was used
It was decided
It was believed ...... etc

Cairo was travelled to by car.

Cairo was reached by car.

intransitive verbs cannot be used in passive except in some known cases this sentence is not one of them:022yb4:

he was said to have traveled NOT to travel

Cairo was travlled to by car

Intransitive verbs are not used in the passive voice except when followed by a prepositional phrase and this doesn't even apply to all intransitive verbs

سبق من حوالى خمسة اعوام ارسل لى احد الزملاء تلك الاسئلة على e-mail وكان ردى كالاتى :
الجمل الآتيه مطلوب تحويلها الى مبنىللمجهول:
? How old are you **

?How are you **
?What's your name **

I'm an English teacher**
وكان الرد:
من الملحوظ ان هذه الجمل فعلها هو verb to be
Intransitive verbs can be passivized in some languages. In English, intransitive verbs can be used in the passive voice when a prepositional phrase is included.
The houses were lived in by millions of people
The passivization can occur without a prepositional phrase, as in "The children slept in the bed," which, in English, could become "The bed was slept in by the children."
It is impossible, however, to make an intransitive verb in English passive without using a prepositional phrase…
…………………………………………………………………………………………………………………………………… ………………………………………………………………………………………………………………………………….
ذكر فى A Comprehensive English Grammar الاتى
Since , in the change from active to passive voice , the subject of the passive construction is formed by the object of the active one , only transitive verbs can be used in the passive voice. So verbs of Incomplete Prediction e.g. seem, be, become , etc….,can never be used in the passive, e.g. He became King could never have a passive form such as A king was become by him.
But certain intransitive verbs can be made into transitive ones by the addition of a preposition . These verbs can be used in the passive voice, e.g.
The bed was slept in by Queen Elisabeth
ولكن البعض ربما يلجا لتمصير تلك الجمل مثل الاتى
. ? How old are you **
Someone asked him about his age. His age was asked about .He was asked about his age.
?How are you ** Someone asked him about his health. His health was asked about. He was asked about his health.
?What's your name **Someone asked him about his name . His name was asked about.
He was asked about his name.
I'm an English teacher**His job is said to be an English teacher .
وهذا ايضا ينطبق على هذا المثال الذى نحن بصدد مناقشته