3. Prepositional-Particle Phrasal Verb

This construction consists of a verb, a particle,

and a preposition. Examples include “I’m looking

 forward to a vacation,” She sat in for me during

my absence,” and “They’re not willing to put up

with it anymore.”

Note that many words serve as both prepositions

and particles. As noted above, the phrase “look

up” can refer to the act of directing one’s attention

 upward, but it also has a figurative meaning:

When one looks something up — or, to be more

formal, conducts research — sight, but not an

upward motion of the head, is involved.

Take care not to confuse phrasal verbs and

compound nouns (sometimes used as adjectives)

that consist of the same words. For example, one

signs up for a class but attends a signup session,

 or simply a signup.

Also, the prepositional phrases “in to” and “on to”

are combined into one word only in certain

circumstances: Into is correct when the reference

is to a location, as in “I went into the doctor’s

office,” a literal reference, as opposed to “I went

 in to see the doctor,” which is figurative. Onto is

correct when you could precede it with up,

 as in “I climbed (up) onto the rock,” but in

sentences such as “I want to hold on to this

 book,” the two-word form is preferred.

Notice, too, that phrasal verbs are generally

colloquial and are seldom suited for formal

 writing; a more succinct alternative is frequently

available. And even in informal prose, writers

should consider omitting extraneous adverbial

particles when a verb alone would do, as in

 “help out” in place of help.