A verb form question tests whether a blank needs a main verb or a form that only describes. Sort the forms by that job, then read the whole sentence and find the blank's subject. A main verb says what its subject does or is; an -ing, to, or having form can't be one on its own. Count the main verbs for that subject, because nearby verbs may belong to other parts of the sentence.
Hints
- Hint 1
Find the subject of the second sentence, then look for a verb that says what that subject does.
- Hint 2
Read past the blank to the period. Which subject does can use belong to, and can helping be a main verb without a helper?
Step-by-step
Sort the forms, then count main verbs
Step 1Sort the forms and find the subject
Sort the choices by whether they can be a main verb, which says what the subject does or is. An -ing, to, or having form can't be one on its own. Who or what is the subject of These structures _____ energy from nutrients into a form the cell can use? The subject is "These structures," so we'll check for its main verb.
- Step 2
Check the verbs after the blank
Do the words after the blank give us that verb? In the cell can use, can use belongs to the cell, not the structures. helping to power growth and repair only describes because helping has no helper such as is. So there's no main verb for the structures yet.
- Step 3
Add the main verb
Which form can complete These structures _____ energy from nutrients? Only convert can serve as the main verb, saying what the structures do. Converting, to convert, and having converted can't do that on their own, so each leaves a fragment, a group of words that can't stand alone as a sentence. Choice D.