Ing-form...
are simply forms of verbs which end ing.
They have many different use in the
grammar oF English.

1- When the simple form of a verb ends in a single
(e), the (e) is dropped before adding (ing).

* have --- having
* write --- writing

2- When a one- syllable verb ends in asingle consonant
(excepting w , x ,and y) preceded by one vowle,
the consonant is doubled before adding ing.

* sit --- sitting
* stop --- stopping

3- A final consonant prceded by two vowels
is not doubled.

* look --- looking
* wear --- wearing

4- When the simple form of averb ends in (ie), the (e)
is dropped and the (i) is changed to before
adding ing.

* die --- dying
* tie --- tying


5- In all other cases, ing is added to the simple form.

* do --- doing
* see --- seeing
* stand --- standing


best wishes,,