What is Gerund???

Gerunds
A gerund is a verbal that ends in -ing and functions as a noun. The term verbal indicates that a gerund, like the other two kinds of verbals, is based on a verb and therefore expresses action or a state of being. However, since a gerund functions as a noun, it occupies some positions in a sentence that a noun ordinarily would, for example: subject, direct object, subject complement, and object of preposition.

Gerund as subject:

Traveling might satisfy your desire for new experiences.
The study abroad program might satisfy your desire for new experiences.
Gerund as direct object:

They do not appreciate my singing.
They do not appreciate my assistance.
Gerund as subject complement:

My cat's favorite activity is sleeping.
My cat's favorite food is salmon.
Gerund as object of preposition:

The police arrested him for speeding.
The police arrested him for criminal activity.
A Gerund Phrase is a group of words consisting of a gerund and the modifier(s) and/or (pro)noun(s) or noun phrase(s) that function as the direct object(s), indirect object(s), or complement(s) of the action or state expressed in the gerund, such as:

Gerund and Gerund Phrase 的功用
以前提及非限制動詞有三種：

1. 不定詞 Infinitive
2. 動名詞 Gerund
3. 分詞 Participle

現在介紹第二種。
什麼是動名詞 Gerund？
動名詞由動詞的 root form + ing 構成。這類詞既有動詞的特性，
亦有名詞的特性。
此外，動名詞加賓語或修飾語，構成動名詞短語 Gerund Phrase。
1. 作主語
例如：
To hunt tigers is very dangerous.﹝不定詞短語﹞
The hunting of tigers is very dangerous.﹝Verbal Noun﹞
Hunting tigers is very dangerous.﹝動名詞短語﹞
Driving a motorcar requires skill.
Speaking rudely is wrong.
* "rudely" 是副詞，不修飾名詞，只修飾動詞，故 "Speaking" 是 Gerund，
不是 Verbal Noun。
There is no stopping him.﹝無法阻止他。﹞
There is no denying this.﹝這是無法否認的。﹞
2. 作賓語
例如：
I like drinking tea.
We enjoy playing table-tennis.
3. 作補語
例如：
His bad habit is drinking wine.
My hobby is collecting stamps.
Our aim is mastering English in the shortest possible time.
4. 放在介詞後面構成介詞短語
例如：

John has a bad habit of spitting everywhere.
* "everywhere" 是副詞，不修飾名詞，只修飾動詞。
You cannot hope to learn a foreign language well without
making efforts.

※ 有些動詞後面只能以 Verbal Noun 或 Gerund 作賓語，
而不能以 Infinitive 作賓語。
例如：
You can hardly avoid meeting her if you both work
in the same office.
I have finished reading a book.
He suggested reading the instructions first.
Would you mind opening the window?
You should practice writing English regularly.
He denied knowing anything about their plans.
We missed seeing that film when it was at the local cinema.
They couldn't help laughing.
We are considering going to America.
§ 動名詞的時態和語態
動名詞本身可以有不同的時態和語態。現以 "do" 為例表列如下：
* 主動語態 被動語態
一般時態 doing being done
完成時態 having done having been done

※ 動名詞的一般時態所表示的動作變化在時間上可以不確定，
或者可與謂語動詞所表示的動作變化可以同時發生。

※ 動名詞的完成時態所表示的動作變化在謂語動詞所表示的
動作變化之前發生。
I hate disturbing people in their work.
﹝我不喜歡在人家工作時打擾他人。﹞
I hate being disturbed in my work.
﹝我不喜歡在我工作時被他人打擾。﹞
Being taught by a good teacher is a blessing.
She did the work without being asked.
I recall having met him somewhere.
I remember having seen the film.
After having finished his lessons, he went home.
He denied having been warned of the danger.
She denied having been told about the news.

The Gerund (the -ing form)

Uses of the Gerund

We can use the Gerund as the subject of a sentence:
Smoking is bad for you.

We can use the Gerund as the object of a verb:
I like sleeping.

We use the Gerund after certain verbs, including:
enjoy, dislike, feel like, deny, mind etc.
Do you enjoy walking to the beach?

We use the Gerund after prepositions:
Reply on, responsible for, tired of etc.
Who's responsible for making this mess?

Note:
Look forward to + ing
I look forward to hearing from you soon
(This is very common when you write letters in English.)