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i have been asked by my students why they cant always use but as a conjunction with none of ......

for example :

There were lots of letters but,none of them were for me correct
there were lots of letters ,none of them were for me. correct

There were lots of letters but,none of which were for me incorrect???
There were lots of letters ,none of which were for me. correct

why is this so i can,t find a good way to explain it .
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AnonymousThere were lots of letters but,none of them were for me correct
there were lots of letters ,none of them were for me. correct

There were lots of letters but,none of which were for me incorrect???
There were lots of letters ,none of which were for me. correct
None of them came is a sentence, or an independent clause.

None of which came is a relative clause, requiring an antecedent. It's not a sentence.

"But," in your examples, can be used to connect only independent clauses.

Edit. Well, I guess that's not very clear.

I invited 25 guests, none of them came. This needs either a conjunction or a semicolon,
because both clauses are independent.

I invited 25 guests, none of whom came. This is fine, because "whom" has an antecedent.

If I remove the prepositional phrase "of whom," the second clause is now independent, and needs a connector:
I invited 25 guests, and/ ;/ but none came.

("None came" is also a stand-alone sentence.)

there were lots of letters ,none of them were for me. correct

This one is not correct, because two independent clauses need a conjunction OR a semicolon.
What you have is called "a comma splice." Two sentences are connected by a comma.
You can use a "full stop" between them (a period and a capital letter), or a conjunction, or a semicolon.
The yellow sentence also needs a capital letter. Emotion: smile - Regards, - A.
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Anonymousa good way to explain it
Draw your students' attention to the word which.

There were lots of letters, but none of them were for me. Correct.
There were lots of letters, none of which were for me. Correct.
There were lots of letters, but none of which were for me. Not correct. It has both but and which.

CJ
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Comments  
Hi,

I should have added that whatever rules or guides or helps you work out for "but" in this specific connection,
also will apply to all of the coordinating conjunctions.

It rained on the packages, so all of them got soaked. okay

It rained on the packages, all of which got soaked. okay

It rained on the packages, so all of which got soaked. incorrect

It rained on the packages, all of them got soaked. (needs connector)

This seems to apply to subordinating conjunctions as well. Emotion: thinking

We had to return the units, all of which were defective.
We had to return the units, because all of them were defective.
We had to return the units, all of them were defective. NO

We had to return the units, because all of which were defective. NO
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