Present participle

The present participle is a form of a verb that ends in –ing and follows another verb to form the present continuous tense. This tense refers to actions or events that are taking place now.
In the above sentences, rising, watching and stealing are present participles. The first two sentences ‘Three balloons are rising steadily into the sky’ and ‘A noisy crowd is watching two cocks fight in a cockpit’ are in the present continuous tense.


More examples of present participle


Position of present participle in a sentence
The present participle can come before


Verb + preposition + present participle


Present participle after conjunction


Simple verb form + present participle
The simple form of the verb and the present participle can be used in place of each other without significantly affecting their meaning.
There is no difference in meaning between the sentences in each pair. 
The conjunction while could be better used with the above sentences.
The use of while indicates an action is still going on (Jill was singing) when another action (I heard) happens.