major key
major mode

The presence of educational and research centers in the city was a major key for its fast economic development.

We've just found what we think may be a major key to the whole problem.

That has been one of the major keys to our success.

We knew that preparation would be a major key in the success of Katie's surgery.

Education is a major key in becoming a more privileged member of the American middle class.

He saw it as a major key to survival and success.

Hair styles are a major key to the desired effect.

Playing the harmonica as it was intended, in its main major key.

Quite often the music is not in a major or minor key.

One major key to the game will be which team stops the other's quarterback.