Some time ago formation of polar stratospheri clouds reported over Antarctica. Why were these formed ? What happens when such clouds break up by warmth of sunlight ?

Why a roling ball stops after some time? What happens to its cause when it completely stops?

Notice the highlighted words in the following sentences. 1. "When I leave,' Sophie said, coming home from school, "I'm going to have a boutique." 2. Jansie, linking arms with her along the street, looked doubtful. 3. "I'll find it," Sophie said, staring far down the street. 4. Jansie, knowing they were both earmarked for the biscuit factory, became melancholy. 5. And she turned in through the open street door leaving Jansie standing in the rain. - When we add "ing" to a verb we get the present participle form. The present participle form is generally used along with forms of "be', " " (is, was, are, were, am) to indicate the continuous tense as in "Sophie was cominghome from school." - We can use the present participle by itself without the helping verb, when we wish to indicate that an action is happening at the same time as another. - In example 1, Sophie "said" something. "Said", here, is the main action. - What Sophie was doing while she was "saying" is indicated by "coming home from school". So we get the information of two actions happening at the same time. We convey the information in one sentence instead of two. I. Analyse the other examples in the same way. II. Pick out five other sentences from the story in which present participles are used in this sense.