Preposition ommission

[Thompson-Tu]

Dear teacher,
I'd like to know if I could omit one preposition from the following sentence.

A helicopter can take off from and land on a roof of a building.

Can I omit the preposition "from" from the sentence and say," A helicopter can take off and land on a roof of a building." ?
Thank you for any answers you could give me.

[mykwyner]

Many teachers (and editors) are fussy about parallel structure, and in this case I'm one of them.

Verbs can share a preposition if the same preposition is appropriate for each verb.

The kids like to splash and play in the pool. It is not necessary, and more than a little awkward to say splash in and play in.

Your example is quite different. One cannot take off on a roof, one must take off from and land on something. That is just how those prepositions work with those verb phrases; I don't think there is a rule other than what I said above.