Hey metallicafan,
Did you check the glossary in the back of the SC book? The entries for "working verb" and "verbal" are quite good, and read as follows:
WORKING VERB
A verb that could be the main verb of a grammatical sentence. A working verb shows tense, mood, and voice, as well as number and person in some circumstances. The use of this term helps to distinguish working verb from verbals, which cannot by themselves be the main verb of a sentence.VERBAL
A word or phrase that is derived from a verb and that funcitons as a different part of speech in the sentence: as a noun, as an adjective (noun modifier), or as an adverb (verb modifier).Ex:
Infinitive: He likes
to walk to the store.
Gerund: I enjoy
walking.
Present Participle: She is on a
walking tour.
Past Participle: The facts
given in the case are clear.
*******
the main thing to remember is that a working verb "works"--it DOES what a verb is supposed to do--
express the action of the sentence. A verbal, by contrast, does NOT "work" as a verb--it's moonlighting as something else, even though it may bear a superficial resemblance to a working verb.
In practice, the test-writers may try to slip in a distractor that only contains a
verbal, not a
working verb-- a sentence MUST have a verb to be a complete sentence. Another way of thinking about it is that
a sentence MUST have a WORKING VERB to WORK--accept no imitation (verbals).****