I have a problem with what adverb to choose in the sentence below:

Because of the fog they could not see clear/clearly enough to land the plane.

In what context do we use 'to see clear" and 'to see clearly'?
Is there a difference in meaning?

thank you in advance
Hello Yoqi

I think "clear" cannot be in general used as an adverb. Only one exception is "shine clear" like in "The Sun shines clear". Also you can use "clear" in the sense of "with clear voice": "She speaks clear" or "We can hear telephone loud and clear". But I don't think we can use it in the sense of "with clear sightedness" or "with optical distinctness". For this, we have to use "clearly". So my choice is "They could not see clearly enough to land the plane".

"... they could not see clearly enough ..." "clearly" is the norm is this type of construction.

But there's an idiom, "to see one's way clear to ...".

They could not see their way clear to make such an important purchase at this time.

Teachers: We supply a list of EFL job vacancies
Hello CJ

My dictionary gives an idiom "see one's way clear to doing something" and says it means "be able and willing to do something". Is it different from your "see one's way clear to do something"?

No. It's the same. For some reason my brain accepts either the infinitive or the gerund there! Most likely the gerund is more used, actually.
Hello CJ

Thank you for your kind confirmation.

Students: Are you brave enough to let our tutors analyse your pronunciation?
thank you for comments.

I found another example with " to see clear"

to see clear to the mountains

Is it the same idiomatic meaning as the one given by Jim?

No, not at all. This is a different meaning. "clear to the" can mean "all the way to the", "the entire distance to the". It's an informal expression.

"No, sir. We don't have that book in stock. You'll have to check at our other branch, and that means driving clear to the next county."

thank you CJ.
Site Hint: Check out our list of pronunciation videos.