from active voice to passive

[Singaporean learner]

Dear teachers,
Can I change the following Active Voice sentences to passive ? My local English teacher told me that it was not possible to change. Is this true? For sentence(b) below, which one is the subject ?

a) Can they build the house ? ( Active voice)
My answer : Can the house be built ( passive voice)
b) Is the killing of wild animals legal ?
My answer : Can wild animals be necessarily be killed ( passive)

On another sentence, is it correct to use a for the word " research" ? e.g. I am doing a research on noise pollution.

Thanks.

[rj1948]

Dear teachers,
Can I change the following Active Voice sentences to passive ? My local English teacher told me that it was not possible to change. Is this true? For sentence(b) below, which one is the subject ?

a) Can they build the house ? ( Active voice)
My answer : Can the house be built ( passive voice)
b) Is the killing of wild animals legal ?
My answer : Can wild animals be necessarily be killed ( passive)

On another sentence, is it correct to use a for the word " research" ? e.g. I am doing a research on noise pollution.

Thanks.

The above sentences can be changed into passive.But in all the above sentences,passive forms weaken the clarity.Sometimes the use of passive can create an awkward sentences.'A research is being done by me on noise pollution.'Doesn't this sentence look awkward?
It's better to avoid passive when the subject is in first person.(I,we..)

Regards,
rj1948.

[Soup]

Can they build the house? Active
Can the house be built? Passive

Is the killing of wild animals legal? Active

____________________
I am doing a research on noise pollution.
I am doing research on noise pollution.

[RonBee]

a) Can they build the house ? ( Active voice)
My answer : Can the house be built ( passive voice)
b) Is the killing of wild animals legal ?
Can wild animals be killed legally?( passive)

Note:

Do not space before end marks.

[Soup]

Note:

Do not space [out] before end marks.