To...extent - Idioms by The Free Dictionary
to some extent
Somewhat; partly; in a limited way or to a limited degree. Your essay would be improved to some extent by tidying up your paragraphs, but your topic on the whole has some fundamental problems. The administration is willing to negotiate to some extent but it is not ready to make any significant changes to the legislation.
to...extent used to show how far something is true or how great an effect it has: To a certain extent, we are all responsible for this tragic situation. ♢ He had changed to such an extent (= so much) that I no longer recognized him. ♢ The pollution of the forest has seriously affected plant life and, to a lesser extent, wildlife. ♢ To what extent is this true of all schools?