Unit: 3 Verb plus ING and TO plus verb.

   GERUNDS: verb plus "-ing", usually used as

            a subject.

            

            Jogging is one way to lose weight.

            (subject)(verb) (infinitive)

            (gerund)

When the prepositions in, at, with, of, for, about and so on are used before a verb, the verb must use -ing.
Let's take a look at some other example sentences using prepositions + -ing:

I'm scared of swimming in the sea.
Thanks for giving me a ride.
My brothers good at playing tennis.
How about taking the bus?
I'm not interested in reading books.

To plus verb after It is...

It is a good idea to write something.

It is rude to cut in line.