1. Using Auxiliary Verbs (be, have, do, will, can, etc.)
* Assertive: She is happy.
Interrogative: Is she happy?
* Assertive: They have finished the work.
Interrogative: Have they finished the work?
* Assertive: You can speak French.
Interrogative: Can you speak French?
* Assertive: He will come tomorrow.
Interrogative: Will he come tomorrow?
* Assertive: We should leave now.
Interrogative: Should we leave now?
* Assertive: The cat is sleeping on the mat.
Interrogative: Is the cat sleeping on the mat?
* Assertive: They are visiting their grandparents next week.
Interrogative: Are they visiting their grandparents next week?
* Assertive: I was reading a book.
Interrogative: Was I reading a book?
* Assertive: We have completed the assignment.
Interrogative: Have we completed the assignment?
* Assertive: She had already left when I arrived.
Interrogative: Had she already left when you arrived?
* Assertive: You might consider applying for that job.
Interrogative: Might you consider applying for that job?
2. Adding 'Do/Does/Did' for Sentences Without an Auxiliary Verb
* Assertive: He likes coffee. (Present simple, no auxiliary)
Interrogative: Does he like coffee?
* Assertive: They live in London. (Present simple, no auxiliary)
Interrogative: Do they live in London?
* Assertive: She went to the store. (Past simple, no auxiliary)
Interrogative: Did she go to the store?
* Assertive: You understand the lesson.
Interrogative: Do you understand the lesson?
* Assertive: My brother plays football every evening.
Interrogative: Does your brother play football every evening?
* Assertive: They enjoyed the concert last night.
Interrogative: Did they enjoy the concert last night?
* Assertive: You work at the local library.
Interrogative: Do you work at the local library?
* Assertive: He studies engineering.
Interrogative: Does he study engineering?
* Assertive: The dog barked loudly.
Interrogative: Did the dog bark loudly?
3. Using Question Words (Wh-words)
* Assertive: He lives in Paris. (Asking about location)
Interrogative: Where does he live?
* Assertive: She bought a new car. (Asking about the object)
Interrogative: What did she buy?
* Assertive: The meeting is at 10 AM. (Asking about time)
Interrogative: When is the meeting?
* Assertive: John won the race. (Asking about the subject)
Interrogative: Who won the race?
* Assertive: She was late because of the traffic. (Asking about reason)
Interrogative: Why was she late?
* Assertive: He solved the problem by using a new method. (Asking about manner)
Interrogative: How did he solve the problem?
Interrogative: Where did the train arrive?
* Assertive: He left early to catch his flight. (Asking about reason)
Interrogative: Why did he leave early?
* Assertive: The new manager will lead the project. (Asking about the subject)
Interrogative: Who will lead the project?
* Assertive: We will meet on Tuesday. (Asking about time)
Interrogative: When will we meet?
* Assertive: She prepared the meal very carefully. (Asking about manner)
Interrogative: How did she prepare the meal?
* Assertive: There are five apples in the basket. (Asking about quantity)
Interrogative: How many apples are in the basket?
* Assertive: The cost is fifty dollars. (Asking about price)
Interrogative: How much does it cost?
4. Using Question Tags
* Assertive: It's a beautiful day.
Interrogative: It's a beautiful day, isn't it?
* Assertive: You can swim.
Interrogative: You can swim, can't you?
* Assertive: He doesn't like pizza.
Interrogative: He doesn't like pizza, does he?
* Assertive: They went to the party.
Interrogative: They went to the party, didn't they?
* Assertive: You finished your homework, didn't you?
Interrogative: You finished your homework, didn't you?
* Assertive: She can't swim, can she?
Interrogative: She can't swim, can she?
* Assertive: It's raining outside, isn't it?
Interrogative: It's raining outside, isn't it?
* Assertive: They won't come, will they?
Interrogative: They won't come, will they?
* Assertive: Let's go for a walk, shall we? (Special case for "Let's")
Interrogative: Let's go for a walk, shall we?
* Assertive: Open the door, will you? (For commands/requests)
Interrogative: Open the door, will you?
