key=important
IMportant is a meaning that key has, the dictionary says. but Is it used in the same way? I don´t think so, that is way I ´d like to ask if you can say:

Verb tenses are key in this exercises

I think that attributively ( prior to the noun) is always correct , that is .. A key issue.

Could someone comment on this ? Thank you

Question

key=important
IMportant  is a meaning that  key has, the dictionary says. but Is it used in the same way? I don´t think so, that is way I ´d like to ask if you can say:

Verb tenses are key in this exercises

I think that attributively ( prior to the noun)  is always correct , that is .. A key issue.

Could someone comment on this ?    Thank you

Answer

Key can mean important, but it often has the narrower meaning of "essential."

An essential issue...

Verb tenses are essential (not just important) in these exercises.

Answer

Both are valid.
Key is an adjective - you can have a brown cat and a cat that is brown, just the same as you can have a key piece of the puzzle and a piece that is key.

In this use, it does mean important. Picture it as a brick in a house that without it, would make the house collapse.