This document discusses different types of clauses in sentences. It explains that sentences can contain main clauses and -ing clauses. -Ing clauses describe an action that is happening simultaneously or as the reason for something. They often use -ing verbs and come before or after the main clause, separated by a comma. Some examples of how -ing clauses are used include to show one action happening during another or to explain why someone did something.

1. A clause is a part of a sentence. Some sentences have two or more clauses:
Jim hurt his arm playing tennis
Main clause -ing clause(gerund)
Feeling tired, I went to bed early.
-ing clause main clause
“Playing tennis” and “feeling tired” are –ing clauses.
If the – ing clause is first (as in the second example), we write a comma (,)
between the clauses. If the – ing clause is first (as in the second example),
we write a comma (,) between the clauses.
We also use –ing when one action happens during another action. We use –
ing for the longer action. The longer action is the second part of the sentence:
Jim hurt his arm playing tennis. (=while he was playing )
Did you cut yourself shaving? (= while you were shaving)

2. You can also use –ing after “while” or “when”:
Jim hurt his arm while playing tennis.
Be careful when crossing the road. (=when you are crossing)
You can also say after-ing:
After finishing her work, she went home.
You can use an –ing clause to explain something or to say
why somebody does something. The –ing clause usually
comes first:
Feeling tired, I went to bed early. (=because I felt tired)
Being unemployed, he hasn’t got much money. (=because he
is unemployed)
Not having a car, she finds it difficult to get around.
(=because she doesn’t have a car)