E4-d Keep the two parts of an infinitive together.

When other words follow the to, they “split” the infinitive, separating to from the base form of the verb. These other words can usually be moved elsewhere in the sentence. Be especially alert to limiting modifiers that split infinitives. (See also E4-c.)

Note: Occasionally, moving intervening words creates a sentence more awkward than the version with the split infinitive. In such cases, leaving the split infinitive may be the better choice.