Grammar focus

1. -ing can sometimes be used to describe two things that happen at the same time, and sometimes describe one thing happening immediately after anoyher. The two parts of each sentence refer to the same person. Besides, we can also put prepositions/ conjunctions before –ing to form a phrase, such as while, when, once, although, until, if etc. And the phrase can be changed into an adverbial clause.

e.g. On seeing her, the king falls in love with her.

When the king sees her, he immediately falls in love with her.