how to what to

[aysaa]

Hi,

I would like to ask 2 questions.

1) Can we use 'what to, how to' with 'not' in the sentences?
First, they didnot know what to eat and what not to eat.

2) Can we use 'why to' in this way as below? Because I have seen that we can't use 'why to' in that way.
Learn how to protect your luggage and why to spend your miles.

Thanks...​

 

[bhaisahab]

Hi,

I would like to ask 2 questions.

1) Can we use 'what to, how to' with 'not' in the sentences?
First, they did not know what to eat and what not to eat. You can't use "how" in this sentence.

​

Bhai.

 

[aysaa]

Thanks for the answer... What about the question two?

 

[emsr2d2]

2) Can we use 'why to' in this way as below? Because I have seen that we can't use 'why to' in that way.
Learn how to protect your luggage and why to spend your miles.

Thanks.
​

That sentence is not natural. The two halves seem completely unconnected but, more importantly, I can't really think of a reason to find out why I should spend my miles (do you mean Air Miles?)

Learn how to protect your luggage and how to spend your air miles.
Learn how to protect your luggage and why you should spend your miles.

I can't think of any natural usage of "why to".