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TOEFL Writing Build a Sentence: wh-word position based on "know" vs "think"

Our big question today is this:
Should the Wh-word go at the beginning of the sentence, or in the middle?

Let’s look at two examples:

  • How old do you think I am?

  • Do you know how old I am?

Both sentences are correct. But these are incorrect:

  • How old do you know I am?
    Do you think how old I am?

The sentence structure looks almost the same. The only difference is the verb: think vs. know.

So why does changing the verb force the Wh-word to move? 🤔

The reason is simple: these verbs ask different kinds of questions.

1️⃣ “Do you know…” → Yes/No Question

When we say:

Do you know how old I am?

We are asking whether you know or not.
The answer should be “yes” or “no.”

Because it’s a yes/no question, the sentence cannot start with a Wh-word.
Instead, it must start with an auxiliary verb like do.

The Wh-word is embedded inside the sentence as part of a noun clause.

Structure:

Do you know + [Wh-word] + [subject] + [verb]?

Examples of similar verbs include verbs of knowledge or fact, such as:

  • know

  • remember

  • understand

  • tell

  • find out

These verbs introduce a noun clause, not a direct Wh-question.

2️⃣ “Do you think…” → Opinion Question

Now look at this sentence:

How old do you think I am?

Here, we are not asking yes or no.
We are asking for your opinion.

The answer might be:

  • 25 years old

  • 30 years old

  • 100 years old! 😄

Since we are asking for the actual answer to the Wh-question, the Wh-word must come at the beginning.

Structure:

[Wh-word] + do you think + [subject] + [verb]?

Verbs that work like think include:

  • believe

  • suppose

  • guess

These verbs ask for real answers, not just yes or no.

Summary: The verb determines where the Wh-word goes.

  • Do you know how old I am? → Yes/No question

  • How old do you think I am? → Real Wh-question

Practice questions

There is a stranger standing by the gate.
We have the words: you / think / is / who / that / do / man / ?

We are completely lost and it’s starting to rain.
should / do / what / you / suppose / we / do

The tire tracks lead toward the woods.
way / which / think / they / do / went / you

This vintage car is beautiful, but it's in rough shape.
cost / how much / imagine / will / do / you / it

Sarah just ran out of the room covering her face.
is / why / do / think / you / crying / she

I need to return these books before the weekend.
know / where / do / you / is / the library

The boss looks very angry and is calling for a meeting.
tell / can / us / what / he / you / wants

The house was empty when I arrived at noon.
remember / you / do / they / left / when

I’ve been pressing every button, but nothing is happening.
explain / can / how / you / works / this