I like the construction of sentences and the juxtaposition of words—not just how they sound or what they mean, but even what they look like.

—Don DeLillo

Subject and Predicate

Every complete, standardized sentence has a subject and a predicate. You were probably taught some time in elementary school that the subject of a sentence is often the noun, pronoun, or phrase or clause the sentence is about, and certainly there is a large overlap between the grammatical concept of a subject and this sense of it as a topic. In most clear sentences, the subject of your sentence will also answer the “who” of the basic narrative question we ask of sentences, “Who does what?” However, it’s more accurate to define the subject of a sentence not as its topic but as the more strictly grammatical issue of what the verb in the sentence agrees with in number. Let’s look at one typically sophisticated college-level sentence to illustrate these ideas:

• Einstein’s general theory of relativity has been subjected to many tests of validity over the years.

A too-quick answer to “who does what?” in this sentence might pick up Einstein, a particularly famous “who,” as the subject. But the grammatical unit that agrees with the verb form “has been subjected” is not “Einstein,” but rather “Einstein’s general theory of relativity.” That’s the grammatical subject of this sentence, but, even so, the sentence is not really “about” Einstein’s general theory of relativity. Rather, the sentence is about subjecting that theory to many tests of validity. Here, then—and in many sentences complex enough to appear in college-level writing—the grammatical subject of the sentence is only tangentially what the sentence is about. To put that another way, the conceptual subject of this sentence is not the grammatical subject of this sentence. Many writers will find it easier to think about the conceptual subject than the grammatical subject, but if you want to get good at negotiating and forming college-level sentences, you’ll appreciate being able to focus on the grammatical subject as what the verb in the sentence agrees with in number.

Just as the “has been subjected” verbal element helps us to identify the grammatical subject of this sentence, it would also lead us to a more pertinent answer to “who does what?” here; i.e., who has subjected Einstein’s theory to such testing? The answer to the “who” question is something like “scholars” or “skeptics” or “scientists at CERN.” The reason those characters don’t appear in this sentence, leaving us unsure exactly who is performing the action signaled by the verb, is because this sentence is in the passive voice—we’ll cover that idea later in this module.

A further point about the grammatical subject in this sentence is that you can distinguish a simple subject from a whole subject (there’s a reason we don’t define subjects this way when you first encounter them in elementary school!). “Einstein’s general theory of relativity” is the whole subject of this sentence: the element that is most fully predicated by the verb. The simple subject is the part of the whole subject that determines whether the verb will be singular or plural. In our example, the simple subject is “theory.” You could change “Einstein” to a different singular or even a plural noun without affecting the verb and / or you could change the nature of the theory without affecting the verb (although of course you would thereby alter the meaning of the sentence; we’re making a grammatical point here, not a conceptual one):

• Newton’s theory of gravity has been subjected to many tests of validity over the years.
• Copernican thinkers’ theory of heliocentrism has been subjected to many tests of validity over the years.

You cannot, however, change “theory” to “theories” without affecting the form of the verb, so “theory” is the simple subject here:

• Einstein’s general theories of relativity have been subjected to many tests of validity over the years.

Here are a couple more examples of subjects in action:

• Although a majority of caffeine drinkers think of it as a stimulant, heavy users of caffeine say the substance relaxes them.
  • whole subject that agrees with the verb “say” = “heavy users of caffeine”
  • simple subject that determines the plural verb form = “users”
  • Notice that the introductory phrase, “Although a majority of caffeine drinkers think of it as a stimulant,” is not a part of the subject or the predicate of the complete sentence.
• In a secure landfill, the soil on top and the cover block storm water intrusion into the landfill.
  • There are two subjects in this sentence: soil and cover. This is a compound subject, making up the whole subject of “the soil on top and the cover.”
  • Notice that the characters in this sentence (the answer to “who does what?”) are not human agents, but rather the inanimate objects “soil” and “cover.” Although humans are social creatures who gravitate toward what other humans are doing as interesting narratives—think about how many of your private conversations revolve around “who does / did what?”—we easily understand non-human agents when we can clearly see them performing some action; i.e., What do soil and a cover do here? They block storm water intrusion.
• Surrounding the secure landfill on all sides are impermeable barrier walls.
  • In an inverted sentence, the predicate comes before the subject. You won’t run into this sentence structure very often as it is pretty rare in standardized, academic English.

The predicate is the rest of the sentence after the subject. Given how we have defined subject above, you won’t be surprised to see that the predicate begins with the form of the verb that agrees with the whole subject. A common definition of a grammatically complete sentence in standardized English is that it has a subject and a verb, e.g. “Water evaporates.” In this case, the predicate is synonymous with the verb. However, predicate also includes the material attached to a verb, known as the complement. In those very common cases, verb + complement = predicate. In other terms you might be familiar with, a predicate can include the verb, a direct object, and an indirect object.

• The pressure in a pressured water reactor varies from system to system.
• In contrast, a boiling water reactor operates at constant pressure.
• The pressure is maintained at about 2250 pounds per square inch then lowered to form steam at about 600 pounds per square inch. (compound predicate)
  • There are two predicates in this sentence: “is maintained at about 2250 pounds per square inch” and “lowered to form steam at about 600 pounds per square inch”

Direct Object

A direct object—a noun, pronoun, phrase, or clause acting as a noun—follows and receives the action of the main verb. To put that another way, the direct object is “acted on” by the verb, so a direct object can be identified by putting what?, which?, or whom? in its place.

• Copernicus refutes Ptolemy.
  • Whom does Copernicus (the subject) refute (the verb)? Answer: Ptolemy (the direct object). Ptolemy is acted on by, or receives, the refutation Copernicus offers.
• Lavoisier used curved glass discs fastened together at their rims, with wine filling the space between, to focus the sun’s rays to attain temperatures of 3000° F.
  • The action (used) is directly happening to the object (discs); i.e., What did Lavoisier use? He used discs.
• The housing assembly of a mechanical pencil contains its workings.
  • The action (contains) is directly happening to what? Answer: to the mechanical pencil’s workings, so workings is the direct object.
• A 20 percent fluctuation in average global temperature could reduce biological activity, shift weather patterns, and ruin agriculture. (compound direct object)
  • The actions (what the fluctuation could do) are directly happening to what? To multiple objects: the fluctuation could reduce activity, could shift patterns, and could ruin agriculture.
• On Mariners 6 and 7, the two-axis scan platforms provided much more capability and flexibility for the scientific payload than those of Mariner 4. (compound direct object)
  • The action (provided) is directly happening to multiple objects (capability and flexibility); i.e. What did the two-axis platforms provide? They provided much more capability and flexibility.

Not all verbs take a direct object. Remember that a direct object is some form of a noun. You can’t create a direct object for the verb “to sleep,” for example (“I sleep bed” or “I sleep Thomas”). Such verbs that don’t take a direct object are called intransitive verbs. Verbs that do take a direct object are called transitive verbs.

Indirect Object

An indirect object—a noun, pronoun, phrase, or clause acting as a noun—receives the action expressed in the sentence. It can be identified by inserting to or for.

• The company is designing senior citizens a new walkway to the park area.
  • The company is not designing new models of senior citizens; they are designing a new walkway for senior citizens. Thus, senior citizens is the indirect object of this sentence.
  • Walkway is the direct object of this sentence, since it is the thing being designed.
• Please send the personnel office a résumé so we can further review your candidacy.
  • You are not being asked to send the office somewhere; you’re being asked to send a résumé to the office. Thus, the personnel office is the indirect object of this sentence.
  • Résumé is the direct object of this sentence, since it is the thing you should send.