INFINITIVE - after interrogative conjunction

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Hmm... quite late to post this, but I have to do it now though it's too late...

Today's lesson is about infinitive after interrogative conjunction. I read the lesson book and it showed me about this issue.

Firstly, after certain verbs, it is possible to use the interrogative conjunction how, what, who, where, when or whether with a to-infinitive.

for examples:

• I wonder who to invite.
• Can you tell me how to get to the station?
• Show us what to do.
• I don't know whether to answer his letter.
• Ask my father where to park the car.
• Did you find out when to pay?

The verbs are know, ask, tell, explain, show, wonder, consider, find out, understand, and others with similar meanings.

Secondly, note that it is not possible to begin a question with How to...? Who to...?

These are typical mistakes:

1. How to tell her?
2. Who to pay?

Instead, we say, for examples:

1. How shall I tell her?
2. How can I tell you?
3. Who should I pay?
4. Who did pay the bill?