Look at the sentences below.
In the first sentence it appears that there are as many as four separate segments which look like partial sentences connected to each other in different ways:
In the second sentence there are two segments:
We can call these segments clauses. Many sentences are short - they contain only one segment or clause. These single-clause units are called simple sentences. Examples of simple sentences might include:
As you can see, it is not possible to divide any of these up into smaller segments that look like sentences. However, many sentences, both in the spoken and the written language, are often longer and more complicated than this simple type; such sentences are called multiple sentences. Sentence 2 (above) is an instance of a sentence which can be broken down into smaller segments or clauses.
Look at the three multiple sentences below:
The sentences can be divided into clauses as follows, and the main clauses are in bold.
In all three sentences each of the main clauses (those without the connecting words and, but and or) can stand on its own as an acceptable sentence - they all act as complete sense units in their own right. Clauses which can stand on their own in this way and have equal importance are referred to as main clauses; this will, of course, also include simple sentences, which contain only one clause. Sentences which are constructed using the linking words and, but, or and the few words which can be used in the same way, like also, too, yet, are called compound sentences. These linking words for compound sentences are known as coordinators since they serve to connect main clauses on an equal footing.
The construction of compound sentences is essentially quite straightforward since we only have to take two or more simple sentences and insert a basic coordinatingword like and, but and or. There are, however many more ways in which clauses can be connected to each other to form longer sentences. The following are just a few examples of how clauses can be conjoined. The main clauses are in bold.
If you examine the sentences carefully, you will notice that only one of the clauses in each sentence can stand alone as a complete idea; these are shown in bold. The remaining clause in each sentence feels unfinished when used on its own. For example a native speaker would find the sense of 'although she's the best in the class' to be incomplete without a second clause expressing an unexpected contrast, in this case 'she did badly in the exams'. The clause which can stand alone is called a main clause, while the clause which depends on the main clause is said to be subordinate.
The range of linking words used with subordinate clauses is much wider than with the linkers in compound sentences. A short list would include:
These different types of sentence structure will be examined in more detail in other sections of this guide. Sentences which are made up of clauses joined in this way are known as complex sentences. Here is an example:
The main clause here is b since this can be used on its own as a complete sense unit.
Note that every sentence needs a subject telling us who or what is doing the action. In these sentences the subject is in bold:
One feature of the levels of sentence and clause is that they both need to include a person(s) or thing(s) carrying out some sort of action. The word denoting the action in a sentence or clause is called a verb, while the person or thing performing the action is typically a noun acting as the subject. The presence of this structure subject + verb, indicates that the collection of words is either a sentence or a clause; without this structure, a string of words is referred to as a phrase.