Please help me with this.

Scratched on stone with a rusty nail.

This is line in a poem on primitive life of man. This line tells how he communicated when there was no paper or pen

The students were asked to fill in a blank space based on this line.

It reads " People used to write .................on stone.

I felt it would have been better if it had been left blank after 'write' as the student might write "on the stone with a rusty nail"

Now I am wondering what answer can be accepted correct. I do not know whether the following expressions, which contains the required words, are natural and can rightly be expected as the answer.

a) with a rusty nail

b) using a rusty nail

I must accept that your question was a bit tricky at first.

People used to write with a rusty nail on stone.This sounds more natural to me.

And suresh don't you think an article should be introduced before 'stone' or make the 'stone' to 'stones'? I have a doubt here.
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Thank you, Prajwal.

I think there is no need for an article here.
If we are talking how people wrote in the accent past in general, we should say: People used to write with rusty nails on stones. We are not talking about "a" stone, or a "the" particular stone but describing people, nails and stones in general. So plurals are used.
Take another example: I am hungry, can I have a banana? Here "a" means 'one".It's ok

But if we talk about things in general, we should use plural nouns i.e. Mangoes, bananas and pineapples are my favorite fruits
How primitive can these people have been if they lived in a civilization that was already manufacturing nails?

Emotion: smile

Students: Are you brave enough to let our tutors analyse your pronunciation?
You know, that actually had crossed my mind!Emotion: it wasnt me

So I did a little reading up on "rusty nails., Man! it's mind opening, I would have never known.....Emotion: geeked
Hi CalifJim,

Thoughtful question!

It is in a peom by Huge Chesterman. Perhaps, the spontaneity flow of ideas was blind to logical reasoning.Emotion: smile
I don't think nails were used for writing at that time. Only sharp rocks were used. However, since the word 'rusty' is used, we will have to think that they actually used nails. Maybe, the poet has used this word to help connect better with the modern generation.

I feel the best sentence would be 'People used rusty nails to write on stones.'
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In the given context, with the given options, I feel the best sentence is ' People used to write with a rusty nail on stone.' Using the word 'used' sounds odd because this word has already been mentioned in the sentence.