If I write a sentence that makes use of two verbs each relying on a different preposition, is it advisable to add commas to structure the sentence and to guide the reader, or is it not necessary (or even detrimental) to do so?

An example:

It has now become clear that Mister Smith had knowledge of, and in fact drew upon, Mister Brown's book.

What about phrases such as the following:

This seems to be the backbone to, and the original contribution of, Mister Brown's book.

1 Answer 1


Yes, it is absolutely necessary.

The information set off in the commas are a parenthetical aside, which require being set off in someway from the text. This is usually done with commas (as you have), or m-dashes (—), or just parentheses.

The rule of thumb I learned is this: If you can remove the phrase and still have a complete sentence, it is an aside.

Better link for the definition and use of asides.

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