Subject and Object Questions

First, let’s review the difference between a subject and an object.

The subject of a sentence is the person or thing that performs the action:

• They need some help
• They  like pizza.
• Smoking causes cancer.
• Susan made a sandwich.
• The tornado damaged my house.

The object of a sentence is the person or thing that is acted upon, or receives the action:

• They need some help
• They like pizza.
• Smoking causes cancer.
• Susan made a sandwich.
• The tornado damaged my house.

OBJECT QUESTIONS IN ENGLISH

Most questions in English are object questions – we want to know about the receiver of the action. These questions follow the QUASM formula: Question word – Auxiliary verb – Subject – Main verb.

For questions in the simple present, the auxiliary verbs are do and does: 

• What do you want to eat?
  We want a hamburguer.
• Who does Romeo love?
  Romeo loves Juliet.
• What does smoking cause?
  Smoking causes cancer.

For questions in the simple past, the auxiliary verb is did:

• What did Susan make?
  Susan made a sandwich.
• What did the tornado damage?
  The tornado damaged my house.

SUBJECT QUESTIONS IN ENGLISH

However, sometimes we want to ask about the subject. We don’t know the person or thing who performed the action, and we want to find  it out.

This type of question is called a subject question, and subject questions do NOT use the auxiliary verbs do, does, and did.

How to form subject questions:

• Who / What + verb in simple present or simple past + object ?

Examples of subject questions in the simple present:

• Who wants some fruit juice?
  We want some fruit juice.
• Who likes Fred?
  Karen likes Fred.
• What causes cancer?
  Smoking causes cancer.

Examples of subject questions in the simple past:

• Who made a sandwich?
  Daniel made a sandwich.
• What damaged your house?
  The earthquake damaged my house.
• Who lied to Sam?
  Jennifer lied to Sam.

Here you can a link for you to practise. And in the case you need further practice, let me know.