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.

—author Don DeLillo

Subject and Predicate

Every sentence has a subject and a predicate. The subject of a sentence is the noun, pronoun, or phrase or clause the sentence is about:

• Einstein’s general theory of relativity has been subjected to many tests of validity over the years.
• Although a majority of caffeine drinkers think of it as a stimulant, heavy users of caffeine say the substance relaxes them.
  • 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.
• In a secure landfill, the soil on top and the cover block storm water intrusion into the landfill. (compound subject)
  • There are two subjects in this sentence: soil and cover.
• Surrounding the secure landfill on all sides are impermeable barrier walls. (inverted sentence pattern)
  • 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.

The predicate is the rest of the sentence after the subject:

• 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”

A predicate can include the verb, a direct object, and an indirect object.

Direct Object

A direct object—a noun, pronoun, phrase, or clause acting as a noun—takes the action of the main verb. A direct object can be identified by putting what?, which?, or whom? in its place.

• The housing assembly of a mechanical pencil contains the mechanical workings of the pencil.
  • The action (contains) is directly happening to the object (workings).
• 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).
• A 20 percent fluctuation in average global temperature could reduce biological activity, shift weather patterns, and ruin agriculture. (compound direct object)
  • The actions are directly happening to multiple objects: reduce activity, shift patterns, and 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).

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 resume so we can further review your candidacy.
  • You are not being asked to send the office somewhere; you’re being asked to send a resume to the office. Thus, the personnel office is the indirect object of this sentence.
  • Resume is the direct object of this sentence, since it is the thing you should send.

Phrases and Clauses

Phrases and clauses are groups of words that act as a unit and perform a single function within a sentence. A phrase may have a partial subject or verb but not both; a dependent clause has both a subject and a verb (but is not a complete sentence). Here are a few examples (not all phrases are highlighted because some are embedded in others):

There are two types of clauses: dependent and independent. A dependent clauses is dependent on something else: it cannot stand on its own. An independent clause, on the other hand, is free to stand by itself.

So how can you tell if a clause is dependent or independent? Let’s take a look at the clauses from the table above:

• when two oppositely charged bodies are brought close to one another
• Since the frequency is the speed of sound divided by the wavelength

All of these clauses are dependent clauses. As we learned in Conjunctions, any clause with a subordinating conjunction is a dependent clause. For example “I was a little girl in 1995” is an independent clause, but “Because I was a little girl in 1995” is a dependent clause. Subordinating conjunctions include the following:

Let’s look at the other clause from our examples:

• which, if current plans hold, will bring nuclear capacity to about 22% of all electrical capacity by 1995

This clause starts with the relative pronoun which (see Relative Pronouns for more information on these). Any clause prefaced with a relative pronoun becomes a dependent clause.