English Grammar: Auxiliaries and Prepositions

In English, auxiliary verbs play an essential role in sentence construction: they help form tenses, questions, negative sentences, or emphatic expressions. The three main basic auxiliaries are: to be, to have, and to do.

This lesson also includes a complete section on prepositions — those small but powerful words that indicate position, time, movement, or relationships between sentence elements.

You’ll find clear explanations, summary tables, bilingual examples, and interactive exercises to help you master each concept step by step.

Auxiliary Verbs in English

There are three main auxiliary verbs in English: to be, to have, and to do. These auxiliaries are considered irregular verbs because they form their past and past participle in a non-standard way.

In addition to these, there are also modal auxiliaries such as can, may, must, shall, will, would, and should. To explore them in detail, see our dedicated lesson: Understanding Modal Auxiliaries.

1. The Auxiliary “To Be”

1.1 Affirmative Form

Long forms:

Short forms (contractions):

Examples:

• I am young. / I’m young.
• You are tall. / You’re tall.
• He is happy. / He’s happy.

1.2 Negative Form

Long forms:

Short forms (contractions):

Examples:

• I am not tired. / I’m not tired.
• You are not late. / You aren’t late.
• He is not ready. / He isn’t ready.

1.3 Interrogative Form

Examples:

• Am I late?
• Are you happy?
• Is he tall?

1.4 Negative-Interrogative Form

Long form:

Short form:

Examples:

• Am I not late? / Aren’t I late?
• Are you not tired? / Aren’t you tired?
• Is he not ready? / Isn’t he ready?

2. The Auxiliary “To Have”

2.1 Affirmative Form

Long forms:

Short forms (contractions):

Examples:

• I have a dog. / I’ve a dog.
• You have a dog. / You’ve a dog.
• He has a dog. / He’s a dog.

2.2 Negative Form

Long forms:

Short forms (contractions):

Examples:

• I have not a dog. / I haven’t a dog.
• You have not a dog. / You haven’t a dog.
• He has not a dog. / He hasn’t a dog. →

2.3 Interrogative Form

Examples:

• Have I a dog?
• Have you a dog?
• Has he a dog?

2.4 Negative-Interrogative Form

Long forms:

Short forms:

Examples:

• Have I not a dog? / Haven’t I a dog?
• Have you not a dog? / Haven’t you a dog?
• Has he not a dog? / Hasn’t he a dog?

3. The Auxiliary “To Do”

The verb “to do” is considered a neutral auxiliary — it has no meaning by itself. It is mainly used to form negative, interrogative and negative-interrogative sentences for all main verbs that are not auxiliaries.

Example:

With the verb to eat (to eat):

• You eat some bread. → (no auxiliary)
• Negative: You do not eat any bread.
• Interrogative: Do you eat some bread?
• Negative-interrogative: Do you not eat any bread?

Note: Do not confuse the auxiliary “do” (neutral, grammatical) with the main verb “to do” which means “to perform / to make”.

Let’s look at a sentence with “do” as both auxiliary and main verb:

I do something new every day.

Negative form:

I do not do something new every day.

Interrogative form:

Do I do something new every day?

Negative-interrogative form:

Do I not do something new every day?

In each sentence, the first “do” is the auxiliary, and the second “do” is the main verb.

Practice: Auxiliary Verbs

Choose the correct auxiliary to complete each sentence. Click “Show answer” to check.

1. ___ I your friend?
   Show answer

   Am
2. He ___ not happy about the decision.
   Show answer

   is
3. They ___ at home right now.
   Show answer

   are
4. We ___ a big family.
   Show answer

   have
5. She ___ a nice car.
   Show answer

   has
6. ___ you have a pen I can borrow?
   Show answer

   Do
7. ___ they not understand the problem?
   Show answer

   Do
8. I ___ not know the answer.
   Show answer

   do
9. ___ she go to school every day?
   Show answer

   Does
10. Why ___ you not speak to him?
    Show answer

    do

4. English Prepositions

Prepositions are short words that indicate position, direction, time, cause, comparison, or manner. They are essential for sentence construction and occur very frequently in everyday English.

In this lesson, you'll explore the most common English prepositions and their different meanings through translated examples. You'll also find key distinctions such as:

• at vs to
• from vs of
• on vs onto

Understanding these small words can make a big difference in your fluency and accuracy.

Let’s start with a selection of common prepositions, explained clearly and illustrated with practical examples.

Practice: Prepositions

Complete the following sentences using the correct preposition. Click “Show answer” to check your response.

1. I live ___ my parents in London.
   Show answer

   with
2. The cat is hiding ___ the sofa.
   Show answer

   under
3. She goes to school ___ bus.
   Show answer

   by
4. The book is ___ the table.
   Show answer

   on
5. He arrived ___ the airport at 7 p.m.
   Show answer

   at
6. We walked ___ the river.
   Show answer

   along
7. She is sitting ___ me.
   Show answer

   beside
8. He came into the house and sat ___ the chair.
   Show answer

   on
9. They traveled ___ France ___ Italy.
   Show answer

   from / to
10. There is a spider ___ the wall!
    Show answer

    on

Challenge Yourself

Choose the correct option for each sentence.

11. My office is ___ the bakery.
    Show answer

    opposite
12. We will meet ___ Friday.
    Show answer

    on
13. She waited ___ two hours.
    Show answer

    for
14. I saw him walking ___ the park.
    Show answer

    through
15. The car stopped ___ the traffic light.
    Show answer

    at

Advanced Preposition Exercises

Fill in the blanks with the correct preposition. Click “Show answer” to see the correct choice.

1. He apologized ___ being late for the meeting.
   Show answer

   for
2. She succeeded ___ passing the final exam with distinction.
   Show answer

   in
3. The book was written ___ a famous journalist.
   Show answer

   by
4. The children hid ___ the table when they heard the noise.
   Show answer

   under
5. We stayed indoors ___ the storm.
   Show answer

   during
6. That’s a problem ___ which we have no solution yet.
   Show answer

   for
7. He leaned ___ the wall while waiting.
   Show answer

   against
8. She divided the cake ___ six equal parts.
   Show answer

   into
9. They’ve been living in Canada ___ 2015.
   Show answer

   since
10. I’m tired ___ listening to excuses.
    Show answer

    of

Want more challenge? Try rewriting these sentences using different prepositions with similar meaning.